In the futures market, traders only need to pay a small amount of money according to a certain proportion of the price of futures contracts as a guarantee for the performance of futures contracts, and they can participate in trading by virtue of futures contracts. This kind of money is the futures margin. In China, futures margin (hereinafter referred to as margin) can be divided into settlement reserve and trading margin according to its nature and function. Settlement reserve is generally paid by member units to the exchange according to fixed standards, and prepared in advance for transaction settlement. Trading margin refers to the actual margin paid by member companies or customers for holding futures contracts in futures trading, which is divided into initial margin and additional margin.

Initial margin is the money that traders need to pay when they open new positions. According to the transaction amount and margin ratio, that is, initial margin = transaction amount × margin ratio. At present, the minimum margin ratio in China is 5% of the transaction amount, which is generally between 3% and 8% internationally.