Shanghai Qingma Investment Management Company launched China Agricultural Products Index (QMAI) on March 2005 1 1. The index selects four categories of commodities: beans, wheat, corn and cotton, and calculates them through arithmetic average and geometric average. It is the weighted average price of four commodities and the average price of four commodities at different times. The percentage change of commodity prices will not change the index. Among the four commodities, the proportion of each commodity in the index is relatively stable, and no commodity has a great impact on the index. The index design has absorbed the general principles and methods of international indexes, and the contract selection follows three basic principles: 1 position size. 2 trading activities. 3 The contract is representative. This design not only reflects the development trend of international index, but also makes the index operation gradually close to international norms.