The invention relates to a trusted connecting system and method based on a power generation control system. The system is formed by an access requester, an access controller and a judgment manager. A logic level comprises an integrity measuring level, a trust evaluation level and a network access control level. The access requester comprises a network access requester body, a trusted client side and a first integrity collector. The access controller comprises a network access controller, a trusted server and a second integrity collector. The judgment manager comprises an authentication manager, a trust evaluator and an integrity checker. The judgment manager comprises a configuration management module, a user identity authentication module, a platform identity authentication module, a dynamic measuring authentication module and an authentication data protection module. According to the dynamic measuring equivalent trust calculating technology, credibility of a connecting object in the system is guaranteed, the illegal external connection and illegal service manipulation process is avoided, viruses are effectively prevented from diffusing in the network, and the safety of system services is improved.