The price limit refers to the extent to which the stock exchange adjusts the price fluctuation based on the closing price of the previous trading day in order to curb excessive speculation and prevent excessive ups and downs in the market. The highest price limit for the stock price to rise to this limit is the daily limit, and the lowest price limit for the stock price to fall to this limit is the daily limit. Price fixing is a measure to stabilize the market. In overseas financial markets, there are also measures such as market disconnection and suspension of trading, speed-limited trading, special quotation system, declared price and trading price limit, adjustment of experts or market intermediaries, and adjustment of trading margin ratio. There are three measures commonly used in China futures market: price limit, suspension of trading and adjustment of trading margin ratio.