I. Introduction

With the gradual integration of China into the global manufacturing system, China enterprises are facing increasingly fierce competition. The research shows that the purchasing cost of raw materials and services in manufacturing industry accounts for 50% ~ 80% of the total cost, and the purchasing cost has become the largest component of enterprise cost, and the importance and urgency of purchasing cost control are becoming increasingly obvious. Domestic industrial and academic circles have conducted in-depth research on procurement cost control methods and achieved a series of research results. The research paper expounds the control methods and measures of procurement cost from different angles, and presents the following characteristics: first, the researchers are mainly enterprise employees; Secondly, the research method is mainly qualitative analysis; Thirdly, from the content, the methods of purchasing cost control can be summarized as follows: cost control method based on purchasing cost definition analysis, cost control method based on purchasing price management, cost control method based on purchasing commodity classification management, cost control method based on purchasing environment analysis and cost control method based on strategic purchasing.

Second, the procurement cost control method analysis

1. Cost control method based on purchasing cost definition analysis. At present, the academic circles have not formed a unified understanding of the definition of procurement cost, and there is still a lack of accurate description and definition of the connotation and extension of procurement cost, which is mainly manifested in four situations: the traditional definition of procurement cost, activity-based costing, life cycle costing and total cost of ownership. He Shen uses the traditional definition of purchasing cost, which is defined as "the sum of manpower, material resources and financial resources spent on purchasing, packaging, loading and unloading, transportation and storage of materials", and puts forward improvement measures from four aspects: the price of purchased raw materials, the management of purchasing departments, transportation fees, storage fees, insurance fees and out-of-stock costs. Zhang Bei and Li Jiangping apply activity-based costing to procurement cost management. They start with the analysis of resource drivers, look for activities that cause procurement costs, take activities as accounting objects, and put forward methods and suggestions to control procurement costs. Peng and Luo expounded the calculation method of life cycle cost, and analyzed the application of life cycle cost calculation method in the procurement of independent innovation products and the obstacles in its application. Sun Lian and others applied the life cycle cost method to the procurement process of telecom equipment, pointing out that the procurement strategy proposed according to the life cycle cost method can help enterprises reduce operating costs and enhance their competitiveness. Zhu Xiaoqin and Zhu Qigui summarized the procurement cost management based on total cost of ownership (TCO), and put forward the enlightenment to the procurement cost management of China manufacturing enterprises. Chen Zhixiang, Liu Zixian and Gong Guangming studied the application of total cost of ownership in the process of purchasing cost control of enterprises in China.

The traditional definition of procurement cost adopts general accounting standards for enterprises, which is not targeted and cannot reflect the whole picture of procurement cost. Activity-based costing can well reflect the indirect costs in the procurement process, but Henrik Agndal and Ulf Nilsson(2007) found that the application of activity-based costing in the long-term procurement management process will generate costs related to supplier relationship management, which makes the application of activity-based costing difficult. The concept of TCO and its very similar concept of life cycle cost have been discussed abroad, and they are mainly based on experience and case studies, but there is basically no research report on this in China. TCO method and life cycle cost method are both strategic procurement cost analysis techniques, which focus on reducing procurement costs and improving the value of purchased goods from a long-term and systematic perspective. From the development trend, academia and industry tend to recognize and accept the concept and concept of TCO and apply it to the process of enterprise procurement cost control. Generally speaking, the cost control method based on the definition and analysis of procurement cost is a basic cost control method, which helps enterprises to identify the source of procurement cost and control it from the source.

2. Cost control method based on purchase price management. Although many enterprises realize that price is no longer the only topic of procurement and supply management, it is still the key factor of procurement management and the most direct and sensitive entry point of procurement cost control. This makes it more difficult to control purchasing cost through purchasing price management, but it also attracts many scholars to study these cost control methods related to price management. There are seven main control methods of purchasing price management: target price method, cost price method, negotiation price, bidding purchase price, centralized purchase price, value analysis and value engineering price, and futures purchase price. Gao Chunhai, Zhang Lin and Ma Ming discussed the target cost planning from the aspects of external drive, basic concept and process, and deeply analyzed the purchasing cost control thought embodied in the target cost planning method. Some researchers have found that enterprises require procurement personnel to understand and master the cost composition of suppliers' products, which can provide a solid and reliable basis for procurement pricing. Negotiation expert Roger Dawson believes that negotiation is the fastest way to make money, and a win-win purchase negotiation price can reduce costs and win net profit for enterprises. Most researchers believe that the bidding price is the result of giving full play to the role of the market, which is conducive to achieving fair competition, optimizing resource allocation and improving procurement efficiency. Gao Feng, Zhu Xinmin, Che et al. discussed the application of centralized procurement in banks, project engineering and group enterprises, and the achievements in cost control. Huang Song studied the cost optimization of centralized procurement of various perishable goods. Tang Xiao, Song Yuqing, Tian Dan and others started with value analysis and functional requirements, and combined with examples to study how to reduce procurement costs more effectively. Gu Yanhua believes that enterprises can hedge their purchases through the futures market or seize some risk-free arbitrage opportunities.

Although the price is only one aspect of the procurement cost, it is very important. In production enterprises, the average value of materials accounts for 52% of sales; If the funds for purchasing equipment are included, this figure will reach 56%. Of course, the proportion of purchase amount to sales varies from 50% to 80% according to different industries. More importantly, procurement has profit leverage effect and asset return effect, which can make a direct contribution to the company's performance. If the purchasing department wants suppliers to maintain a fair price, it needs the purchasing department to have its own methods and experience in determining the price. Although the above-mentioned cost control strategies based on purchasing price management cannot cover all price strategies, they are all effective methods often adopted by enterprises. The purchasing department of an enterprise will comprehensively use one or more price strategies to win a fair purchasing price for the enterprise and improve the ability of the enterprise to control the purchasing cost.

3. Cost control method based on classified management of purchased goods. It is a basic premise to reduce the purchase cost to classify the purchased goods and make different purchase decisions accordingly. Guo and others put forward an improved ABC classification-A+ AA- B+ BC classification: all materials are divided into six categories: A+,A, A-,B+,B and C, and each category is given a category label. Through category labels, related materials can be quickly located, which is convenient for enterprises to jointly purchase, thus realizing systematic management of procurement and inventory and reducing the total procurement cost. Starting from the enterprise's own experience, the Party analyzes the effectiveness of ABC classification in purchasing cost control. Wu Minjie compares the difference between MRO material procurement and direct means of production procurement, introduces the characteristics of transnational MRO procurement, describes the transnational procurement situation of domestic and foreign industrial enterprises, and puts forward the transnational MRO integrated procurement mode of domestic industrial enterprises. Because purchasing is not just about buying, but more importantly, management. Classified management of purchased goods can reduce the procurement cost, which is mainly reflected in improving the procurement process, optimizing inventory and promoting the implementation of supply chain management. These aspects are not only the focus of procurement management, but also the starting point of procurement cost control.

The cost control method based on the classified management of purchased goods closely links the work of purchasing department with the quality control of production department, inventory management of storage department and vehicle scheduling of transportation department, which is conducive to smooth communication and full cooperation between departments. At the same time, this control method has also become the basis for selecting suppliers. In addition, procurement activities generally begin with determining procurement requirements and commodity types. In this sense, the cost control method based on the type of purchased goods is also a basic cost control method.

The above three procurement cost control methods are closely related to the purchased goods. Generally speaking, the control of procurement cost is considered from the perspective of goods, focusing on the purchased goods themselves, without fully considering enterprises, organizations outside enterprises and their relationships. 4. Cost control method based on purchasing environment analysis. The control method based on purchasing environment analysis takes the enterprise itself, the environment in which the enterprise is located and the relationship between them as important factors of purchasing cost control. Purchasing environment is the existence condition for purchasing workers to organize purchasing activities, including internal environment and external environment of enterprises. Yuan analyzed the methods of controlling the procurement cost of EPC project from aspects of perfecting the procurement system, establishing a good internal assessment mechanism and training system. Que Weizhong believes that it is absolutely necessary and extremely effective to establish a procurement management platform, standardize the procurement business process and the behavior of procurement personnel, and put an end to "black-box operation" and procurement corruption. Tang Qinghai suggested that the procurement of engineering projects should make full use of the procurement environment and establish a good market information mechanism.

The improvement of the internal environment of an enterprise can prompt the purchasing department to make better purchasing decisions, communicate effectively with other departments, enhance the transparency of business, and produce better incentive effects, thus improving the position of the purchasing department in the company, reducing operating costs and material purchase prices, reducing the number of waste products and producing better decisions. The external procurement environment of enterprises is procurement and supply market, and the increasingly turbulent global supply market makes the research on procurement market a crucial activity. The sudden restriction of export trade between countries, the disappearance of suppliers due to bankruptcy, the constant change of exchange rate, the "9. 1 1 incident" and the current "sub-commodity crisis" in the United States have brought great uncertainty to the global supply market. Through the study of the procurement market, we can grasp this information in advance, avoid the unfavorable factors that lead to the increase of procurement costs due to the supply market risks, seize the opportunity to reduce procurement costs, enhance the control ability of enterprises on procurement costs, and realize the procurement objectives of enterprises.

5. Cost control method based on strategic procurement. Procurement decision-making includes three aspects: strategic level, tactical level and operational level. Strategic purchasing belongs to the strategic decision of purchasing decision. Procurement agency (outsourcing), e-procurement, JIT procurement, joint procurement, global procurement, green procurement and procurement under the supply chain environment are all part of the strategic decision of enterprises. Wang Feng pointed out that purchasing agent, as a new material purchasing mode, will surely be recognized by more enterprises and become a new choice of purchasing cost for many enterprises. By modeling the total cost of ownership under specific environment and random conditions, Wang Xiaobin and others know that e-procurement creates value for procurement through different aspects in the whole process before, during and after the procurement transaction. Nie Lanshun took the supply chain composed of suppliers and buyers as the research object, and established a JIT procurement batch division decision model considering transportation costs. Tang Donghui believes that we should fully understand the cost of green procurement from a dynamic perspective. Guo Haisen and Ye Peng proposed that the best way of strategic procurement is to establish a win-win strategic partnership. In the face of the sudden global financial turmoil, some scholars suggested that China automobile industry should conduct joint procurement and heating; Some scholars believe that China enterprises are now facing global competition, and procurement should also adapt to the trend of globalization. The cost control method of strategic procurement is not limited to reducing the procurement cost of enterprises, but focuses on enhancing the core competitiveness of enterprises, clarifying the development strategy of enterprises, strengthening the cooperative relationship with suppliers and customers, and improving the supply chain management ability of enterprises, so as to provide better services to customers and finally win long-term profits for enterprises. The purchasing method mentioned here is not a simple cost control method or measure, but a purchasing strategy. Their application and implementation need to be considered from the perspective of enterprise strategy and combined with the core competitiveness of enterprises in order to achieve the purpose of cost control.

From the content point of view, the domestic research on strategic procurement mostly belongs to the idea and concept of proposing or advocating a certain procurement strategy, and there is little research on its application in practice. In this regard, foreign research is more in-depth. Jean Nollet et al. (2005) discussed the advantages and disadvantages of joining the procurement alliance to implement joint procurement from five aspects: profit, supply market, group size, membership and beneficiaries. Pervez N.Ghauri(2008) discussed the beneficial support and contribution of global supply network to IKEA's market-driven strategy. Dothang Truong(2008) surveyed 359 professional purchasers online and found that e-procurement can actively promote the development of e-commerce. Jon Edgell(2008) summarized four development trends of global procurement in 2008, and pointed out that China will remain an important global procurement market due to the weak US dollar and China's huge cost advantage. Judging from the research on strategic procurement abroad, foreign countries have been studying the implementation of strategic procurement in enterprises and have begun to sum up experiences and lessons. This gives our country an important enlightenment: strategic procurement has crossed the concept stage and gradually entered the implementation stage, which requires our country's research to keep up with this pace.

Third, the research trend of procurement cost control

With the increasingly fierce global competition, procurement is regarded as the "third profit source" for enterprises to tap potential profits. Controlling procurement cost has become the focus of enterprise managers and procurement practitioners, and the following three aspects will be further studied.

1, quantitative method of purchasing cost control. At present, the research on procurement cost control methods in China is basically in the qualitative research stage, and some control methods and measures put forward mostly come from management experience and lessons, and a scientific and quantifiable decision-making system has not yet been formed. As peter drucker, a management guru, said, "What can be measured can be accomplished", I believe that the research on quantitative methods of procurement cost control will be a direction of future efforts.

2. How do small and medium-sized enterprises implement procurement cost control? In the study of procurement cost control, many documents either do not distinguish between enterprise types or take large enterprises and multinational companies as examples, but pay little attention to small and medium-sized enterprises. Many foreign researchers, such as Mihir A.Parikh et al. (2005), analyzed a transformation model of small enterprise procurement and a successful application case in practice; Andreas R.Holter et al. (2008) put forward a variety of tools to improve the procurement of transportation services for SMEs, thus expanding the procurement decision-making power of SMEs; John Ramsay(2008) bluntly pointed out that more attention should be paid to SMEs in procurement and supply management. In addition, from the scale point of view, there are about 42 million small and medium-sized enterprises in China at present, which has great potential to save procurement costs. Therefore, it is of great practical significance to study the procurement cost control of small and medium-sized enterprises.

3. Research on the application of management accounting in purchasing cost. The current management accounting methods, such as activity-based costing, life cycle costing and total ownership costing, all have their limitations. Although the total cost of ownership has been gradually recognized and used, there are still many problems in its specific implementation, which still need to be improved and perfected. Therefore, the in-depth study of procurement cost control methods needs to improve the existing accounting methods on the one hand; On the other hand, it is necessary to introduce new management accounting to promote the scientificity and practicability of purchasing cost accounting.