The influence of spot parity principle on futures contract pricing comes from premium. Theoretical price of futures = spot price+premium. When the quality of goods is lower than the normal level, the buyer asks the seller to reduce the price, which is called premium. When the quality of goods is higher than the normal level, the seller requires a certain premium, and the selling price will be higher than the normal price. Theoretical futures price = spot price+premium. If the premium is subdivided: storage cost+loan interest+holding income. Futures prices are theoretically based on spot prices. Due to the standardization of futures contracts, commodities of the same quality are required to circulate in the market. Futures prices are representative. Compared with spot prices, the correlation between spot prices and futures prices is very high.