When each transaction in forex futures trading is concluded, both the buyer and the seller must pay a certain margin to the broker in accordance with the relevant regulations of the futures exchange, so as to ensure that the buyer and the seller fulfill their obligations. After receiving the customer's deposit, the general broker transfers part of the deposit from the customer to the clearing house in accordance with the prescribed proportion, and at the same time charges the customer the transaction fee as the guarantee price. The margin of futures trading is not only the function of preventing the parties from defaulting, but also the basis of the clearing house settlement system. Foreign exchange futures margin can be divided into initial margin and maintenance margin. The initial margin is the margin paid by the customer at the beginning of each transaction, and the margin is different in different transaction currencies. The amount of margin payable shall be determined by the clearing house and the exchange, and adjusted according to the maximum fluctuation range of futures prices. Usually, each contract costs 900 ~ 2800 dollars. The margin amount of foreign exchange futures is calculated according to the number of positions held at the close of each day. If the deposit paid by a member is insufficient, it shall be made up the next day. Some exchanges charge higher margin for futures contracts delivered in the current month. The trading ownership increases or decreases the initial margin amount, and also has the right to charge more or less margin to a single clearing member. In the United States, deposits can be partially used as federal bonds and so on. In LIFFE, the deposit must be deposited in the clearing house account in cash. The clearing members settle the profit and loss every day.