In the electronic payment system of e-commerce, there is the transmission of transaction information between customers, merchants and banks, including ordering information that only merchants can see and payment information that only banks can see. Because the payment information that the bank needs to know is transmitted to the bank by the customer through the merchant, the purpose of double signature is that in the transaction process, when the customer transmits the ordering information and payment information to the merchant, the ordering information and payment information are isolated from each other, and the merchant can only see the ordering information but not the payment information, and transmit the payment information to the bank unchanged; Moreover, merchants and banks can verify the consistency of ordering information and payment information, so as to judge whether the ordering information and payment information have been modified during transmission.