Green food refers to safe, high-quality, nutritious food that is pollution-free and is produced according to specific production methods in accordance with the principle of sustainable development. It is recognized by a specialized agency and is allowed to use the green food mark (Figure 2). Green food certification refers to the process in which an authoritative third-party organization tests food according to relevant green food standards, issues an inspection report, and awards green food labels to foods that meet the standards.

At present, green food standards are divided into two technical levels, namely AA-level green food standards and A-level green food standards.

AA-level green food means that the environment of the place of production meets the requirements of NY/T391-2000 "Environmental Quality Standard for Green Food Production Places" and the production process does not use chemically synthesized fertilizers, pesticides, veterinary drugs, feed additives, food Additives and other substances that are harmful to the environment and human health are produced according to organic production methods. The product quality meets the green food product standards. Products that have been recognized by specialized agencies and are allowed to use the AA-level green food mark.

Grade A green food means that the environment of the place of production meets the requirements of NY/T391-2000. The production process strictly follows the guidelines for the use of green food production materials and the requirements of production operating procedures, and uses limited chemical synthesis production materials in a limited amount. Product quality complies with green food product standards, and is certified by a specialized agency and is licensed to use the Class A green food mark.