In the United States, the pricing mode and hedging operation mode in the spot market of agricultural products, as well as the spot trading in the futures market and the final judgment of delivery are all based on the basis of basis. Similarly, in order to do a good job in basis trading, both parties to the transaction, especially the basis seller, must seriously study the basis change law between the spot and futures of the goods involved. This is very important for the choice of hedging opportunity of the basis seller, the formulation of the buyer's pricing strategy and the negotiation of premium between the buyer and the seller. Therefore, it is very important to master the research methods of basis and find the law of basis change from a large number of historical data as the theoretical basis for guiding basis trading.