The present invention relates to a security access control method and system for wired local area network, the method includes the following steps: 1) a requester (REQ) negotiates the security policy with an authentication access controller (AAC); 2) the requester (REQ) and the authentication access controller (AAC) authenticate the identity; 3) the requester (REQ) negotiates the key with the authentication access controller (AAC). The direct identity authentication between the user and the network access control device is realized by the present invention; the negotiation and the dynamic update of the session key for the link layer data protection are realized; a variety of network architectures such as the enterprise network, the telecommunication network are supported; the scalability is good, the multiple authentication methods are supported; the authentication protocols with different security levels are supported, the requirements of the various subscribers are satisfied; the sub-modules of the protocol are independent, flexible, and easy to be accepted or rejected.