1. Stock index futures is a financial derivative, and its trading method is futures trading with stock index as the subject matter. In stock index futures trading, traders need to set a limit order to set the price range of buying or selling, which is the price limit of stock index futures.

2. The price limit of stock index futures refers to the price range set by traders before trading. If the price of the futures contract is within the price range set by the trader, the transaction will be successfully concluded at the best price between the buyer and the seller. If the price of the futures contract exceeds the price range set by the trader, the transaction will not be concluded, but will wait for the emergence of a new limit order.

3. In stock index futures trading, traders can flexibly use limit orders to control their trading risks. If a trader sets a buying limit higher than the market price, he can get a better price when the price rises. Similarly, if a trader sets a selling limit below the market price, he can get a better price when the price falls. Therefore, in the stock index futures market, traders' limit orders can help them maximize their returns and reduce their risks.