Stock index futures have crowding out effect on the stock market, because the total amount of funds in the market is limited. After the opening of stock index futures, a large number of stock investors sold stocks to speculate on stock index futures. At present, the daily trading volume of stock index futures has far exceeded that of Shenzhen and Shanghai stock markets. Except for a few commodity futures funds, most of them come from the stock market. In fact, in Europe, America, Japan, South Korea and stock index futures, the short-term decline is around 20%. When investors who want to speculate in stock index futures open accounts, they will naturally reach a balance and the stock market will be on the right track again.