A trusted network connect (TNC) system based on tri-element peer authentication (TePA) is provided. An network access requestor (NAR) of an access requestor (AR) is connected to a TNC client (TNCC), and the TNCC is connected to and integrity measurement collector (IMC1) through a integrity measurement collector interface (IF-IMC). An network access controller (NAC) of an access controller (AC) is connected to a TNC server (TNCS) in a data bearer manner. The TNCS is connected to an IMC2 through the IF-IMC. A user authentication service unit (UASU) of a policy manager (PM) is connected to a platform evaluation service unit (PESU) through an integrity measurement verifier interface (IF-IMV). Thus, the technical problems in the prior art of poor extensibility, complex key agreement process, and low security are solved. TePA is adopted in both the network access layer and the integrity evaluation layer to implement mutual user authentication and platform integrity evaluation, so that the security of the entire TNC architecture is improved.