The so-called "fuse" system means that when the volatility interval touches the specified number of points, the transaction will stop for a period of time, or the transaction can continue, but the price interval cannot exceed the specified number of points. Because this situation is similar to that when an excessive current passes, the fuse will blow and the electrical appliance will be protected, so it is called fuse system figuratively. For example, 1, the stock index will continue to maintain a unilateral trend during the fuse period, which will definitely cause some panic to the market. Therefore, a considerable number of pending orders will be accumulated at the fuse price, which may lead to the direct closure of the board after the fuse period, which will expand the market risk to a certain extent. 2. During the fuse period, the stock index tends to be stable, or adjusted, and the market turmoil caused by the fuse start will also tend to be calm. After the fuse is over, stock index futures will tend to calm down. 3. The pending orders during the fuse period can be used as an effective indicator of real-time market popularity, and the situation after the end should be roughly judged according to the number of pending orders and the transaction situation. For example, there are a large number of pending orders, indicating that the market is sure of the continuation of the market, so the price may continue to be unilateral under this inertia; On the contrary, if only the fuse price is touched and the pending order has no obvious positive intention, then it can be judged that there is no strong impulse in the real-time market. In foreign exchanges, there are two forms of "fuse" system, namely "fuse" and "fuse". The former refers to stopping trading for a period of time after the price touches the fuse point; The latter means that trading can continue for a period of time after the price touches the fuse point, but the quotation is limited to the fuse point. In a falling market, drastic and disorderly price changes are more destructive to futures and spot markets than to a rising market. Therefore, most of the fuse mechanisms used in foreign securities and futures markets are only used in falling markets, and do not involve rising markets. Stock index futures are financial products based on stock indexes. The fuse mechanism used in the relevant stock index futures contracts of many foreign futures exchanges also takes into account the fuse state of their stock market transactions, so as to realize the corresponding futures. According to the Measures for Risk Control and Management of China Financial Futures Exchange, the fuse mechanism adopted is "continuous fuse", which is applicable to both rising and falling markets. Specifically, after the daily market opening, the declared price of the stock index futures contract touches the fuse price (6% of the settlement price of the previous trading day) and lasts for 5 minutes, and the fuse mechanism starts immediately and lasts for 5 minutes. During this period, the transaction declaration will continue to match transactions within the fuse price range according to the principle of liquidation priority and time priority. The fuse mechanism is only started once a day, and there is no fuse mechanism within 30 minutes before the market closes, and there is no fuse mechanism on the last trading day. The price limit range is 10% of the settlement price of the previous trading day, and the price limit range of the last trading day is expanded to 20%.