NDF refers to non-deliverable forward foreign exchange, which is a mode of forward foreign exchange trading and is used for offshore currency trading in countries and regions that implement foreign exchange control. At the time of transaction, both parties to the transaction determine the face value, forward exchange rate and maturity date of the transaction. Two days before the maturity date, determine the spot exchange rate of the currency on the maturity date. Both parties to the transaction calculate the profit and loss according to the difference between the spot exchange rate and the forward exchange rate at the beginning of the transaction, and the losing party pays the beneficiary in convertible currencies such as US dollars.