Stock index futures mainly play the role of risk aversion, diversification and transfer. This is achieved through hedging. Investors can achieve the purpose of risk aversion by reversely operating in the stock market and the stock index futures market, which helps investors avoid price risks in the stock spot market. For the entire market, stock index futures are helpful to resolve the systemic risk of the stock market, that is, when systemic risk occurs, the market prices of various stocks will change in the same direction. It is obvious that the decentralized investment of the stock market alone cannot avoid the price as a whole. Risk of change. Stock index futures have a short selling mechanism. Investors who are worried that the stock market will decline can sell stock index futures contracts to mitigate the negative impact of collective selling on the stock market and effectively hedge the systemic price risk of the overall decline in the stock market. In addition, because stock index futures use a margin trading system and low transaction costs, they are widely used by institutional investors as a means to improve the efficiency of fund allocation. Institutions can use very little funds to buy stock index futures, so that they can obtain the average return of the stock market and improve the overall allocation efficiency of funds.