The basic feature of hedging is that the same commodity is bought and sold in the spot market and futures market at the same time, that is, at the same time of buying or selling the real thing, the same amount of futures is sold or bought in the futures market. After a period of time, when the price changes make the profit and loss in spot trading even, the losses in futures trading can be offset or compensated. Therefore, hedging mechanisms are established between "now" and "period" and between short-term and long-term to minimize price risk. After all, the futures market is an independent market different from the spot market, and it will also be affected by some other factors, so the fluctuation time and amplitude of futures prices are not necessarily the same as the spot price; In addition, in marketing unit, where the futures market is regulated, the number of operations in the two markets is often not equal, which means that the hedger may gain additional profits or losses when offsetting the gains and losses.