A method and a system for network access control are provided, which are based on cipher code mechanism. After a visitor has raised an access request, an access controller in the destination network processes the access request and initiates an authentication request on the visitor identity to an authentication server through the visitor. The access controller in the destination network accomplishes the authentication on the visitor identity according to the public authentication result of the authentication server transferred by the visitor, and performs according to the authorization policy the authorization management on the successfully authenticated visitor. The present invention solves the problem of incapableness of performing the access control when the access controller can not directly use the authentication service provided by the authentication server. The present invention can sufficiently satisfy the real application requirements of access control on visitor.