1, SET is the abbreviation of secure electronic transaction, and it is an open electronic payment protocol standard based on electronic money established for online transactions on the Internet. 2. The goal of 2.set is to ensure the safe transmission of information on the Internet, to ensure that the information of e-commerce participants is isolated from each other, to solve the problem of multi-party authentication, and to ensure the real-time performance of online transactions. Promote the compatibility and interoperability of software developed by different manufacturers, which can run on different hardware and operating system platforms. 3. The 3.set protocol specification covers consumers, online stores, acquiring banks, electronic money and authentication centers (CA), etc. 4.set protocol mainly uses symmetric encryption, public key encryption, hash algorithm, digital signature technology and public key authority mechanism. With the application of these technologies, SET can ensure the confidentiality, consistency and integrity of transaction data, realize the authentication of merchants, provide consumers with a means to authenticate the identity of merchants, promote the compatibility of software developed by different manufacturers, and realize the interoperability function on different hardware and operating system platforms. To sum up, the SET credit card payment form represents the development direction of e-commerce payment and settlement.