With the constantly expansion of network scale, the problems of network security become more and more intractable. Currently, how to establish trusted network has been a research hotspot. The key technology of trusted network is authentication, the access authentication; management and control of user and device are the base for various network security schema. In this paper, a new network access model is proposed, consisting of NASREQ and EAP application of diameter protocol, PAA and EP function of PANA protocol, and authenticator function of EAP protocol. The NAS prototype system is designed and implemented, and the system is tested. By performance analysis, the result proves that the system basically satisfies requirements of a NAS defined by diameter, EAP and PANA protocols. The new method combines the merits of digital certificate and can promotes the control-ability and manageability of network.