Theoretically, there are many effects, such as using stock arbitrage to hedge the stocks that have been bought and shorting when the market is bad. These functions of stock index futures will theoretically have a great impact on the stock market. But theory is theory after all. In the case of immature domestic capital market, spot arbitrage and hedging are only theoretical things and cannot be implemented at present. Because according to the relevant national laws and regulations, stock index futures can only hedge 20% of the stock volume, and 80% of the risk exposure cannot be hedged, so hedging and arbitrage are theoretical things in China. At present, stock index futures is a speculative market, which has no other substantive functions except speculation.