In the futures market, investors try their best to keep the premium rate at a balanced level. Futures discount can not only refer to the price relationship between spot and delivery month, but also refer to the price relationship between alternative delivery and standard delivery in physical delivery, and also refer to the price relationship between different delivery places of goods. Premium reflects the specific price relationship between a commodity and a target under certain conditions, so the change of premium has a great influence on futures prices, and investors are also very sensitive to the change of premium.