trade financing is one of the businesses of banks. Refers to the short-term financing or credit facilities provided by banks to importers or exporters related to import and export trade settlement; In international trade activities, buyers and sellers may distrust each other, and after the buyer is worried about the advance payment, the seller will not deliver the goods according to the contract requirements; The seller is also worried that the buyer will not pay after delivery or submission of shipping documents. Therefore, two banks are needed as guarantors of buyers and sellers, to collect and pay documents on their behalf, and to replace commercial credit with bank credit. The instrument used by banks in this activity is the letter of credit.