Futures contract margin: In the futures market, traders can participate in futures contract trading by paying a small amount of funds according to a certain proportion of the futures contract price as the financial guarantee for the performance of futures contracts. This kind of funds is the futures margin.

In the process of holding positions, traders will have floating profits and losses (the difference between settlement price and transaction price) due to the constant changes of market conditions, so the funds actually available in the margin account can be increased or decreased at any time. Floating profit will increase the balance of margin account, while floating loss will decrease the balance of margin account. The minimum balance that must be kept in the margin account is called maintenance margin. Maintenance margin: the settlement price is adjusted to the position, and the margin ratio is adjusted to xk(k is a constant, which is called the maintenance margin ratio, which is usually 0.75 in China).