A system and method for authenticating network access of a terminal is described. The method may include sending, by the terminal, a user identity authentication request including first authentication information and second authentication information to an authentication server, where the first authentication information is used to authenticate a user identity of the terminal, and the second authentication information is used to determine a platform corresponding to the terminal. The method may also include after receiving user identity authentication acknowledgment information sent by the authentication server, sending, by the terminal to the authentication server, a platform identity authentication request including third authentication information used to determine the platform corresponding to the terminal. The authentication server sends platform identity authentication acknowledgment information to the terminal when determining that the platform corresponding to the second authentication information is consistent with the platform corresponding to the third authentication information.