A trusted authentication system and method for network transactions belongs to the technical field of trusted authentication for network transactions. The bottom layer of the system supports two mainstream operating systems, Windows and Linux; on top of the bottom layer support is the basic management module, which are communication management module, certificate management module and database management module; on top of the basic management module is the fourth-party authentication domain ; Also includes user domain, e-commerce domain and third-party payment domain, etc. The trusted authentication method includes steps: 1) When a network transaction occurs, the user logs in to the secure client, uploads a digital certificate for digital authentication, and e-commerce and third-party payments also upload their digital certificates for corresponding digital authentication; 2) when After the digital authentication is passed, the user downloads the behavior certificate through the user behavior certificate download module, and the three parties officially enter the transaction process; and so on. The invention has good expansibility, portability and versatility, flexible and convenient configuration and deployment, and does not need third-party software support.