The invention relates to a network access authentication method applicable to a satellite mobile communication network. The network access authentication method comprises four steps of user registration, user management, mobile authentication and update of authentication; an effective network access authentication protocol is of great importance for the security of the satellite mobile communication network. The network access authentication method is characterized in that the authentication role of a gateway station is emphasized and the authentication calculation load of an NCC (Network Control Center) is reduced; common attacks such as masquerading, tampering and replay of any party can be resisted, and meanwhile, integrity protection on the transmitted data is realized, and therefore, the security of the satellite mobile communication network is greatly improved.