According to the different manufacturing processes and shapes, natural rubber can be divided into cigarette gum, particle gum, crepe gum and latex. However, cigarette gum and particle gum are the main products in the market. Tobacco gum is made by curing, drying, smoking and other processes, and most of the natural rubber imported from China is tobacco gum; Granular rubber is made by curing, granulating, drying and other processes. Natural rubber made in China is basically granular rubber, also called standard rubber. Cigarette gum is generally classified according to its appearance, which is divided into six grades: super grade, first grade, second grade, third grade, fourth grade and fifth grade. Those that fail to reach the fifth grade are classified as external coating; Granular rubber is generally classified according to internationally unified physical and chemical properties and indicators. These physical and chemical properties include impurity content, initial plasticity value, plasticity retention rate, nitrogen content, volatile matter, ash content and color index. Among them, the impurity content is the leading index, which is divided into five grades according to the amount of impurities, such as 5L, 5, 10, 20 and 50. The contract delivery grades of natural rubber in Shanghai Futures Exchange are domestic first-class standard rubber SCR5 and imported tobacco flake rubber RSS3, among which domestic first-class standard rubber SCR5 is also commonly known as No.5 standard rubber, and all quality indexes of Natural Rubber GB 808 1 ~ 8090-87 issued and implemented by the State Bureau of Technical Supervision are implemented. Imported cigarette rubber RSS3 implements the "International Standard of Natural Rubber Quality and Packaging" determined by the International Rubber Quality and Packaging Conference.