A secure access method, wherein the method comprises: receiving, by a first authentication server, a first message from a non-3rd generation partnership project, 3GPP, access device, wherein the first message carries a fast re-authentication identifier of a terminal; determining, by the first authentication server, that fast re-authentication is allowed; performing, by the first authentication server, fast re-authentication with the terminal; sending, by the first authentication server, a second message to a home subscriber server, wherein the second message carries a registration type identifier, an identifier of the terminal, and an address of the first authentication server, and the registration type identifier is used to indicate that current secure access of the terminal is secure access using a fast re-authentication procedure; receiving, by the first authentication server, a registration success indication from the home subscriber server; and sending, by the first authentication server, an access success indication to the terminal based on the registration success indication, wherein the receiving the registration success indication is performed if: determining, by the home subscriber server, based on the identifier of the terminal that an address of an authentication server corresponding to the terminal is not stored; or determining, by the home subscriber server, based on the identifier of the terminal, that the address of the first authentication server is stored. receiving, by a first authentication server, a first message from a non-3rd generation partnership project, 3GPP, access device, wherein the first message carries a fast re-authentication identifier of a terminal; determining, by the first authentication server, that fast re-authentication is allowed; performing, by the first authentication server, fast re-authentication with the terminal; sending, by the first authentication server, a second message to a home subscriber server, wherein the second message carries a registration type identifier, an identifier of the terminal, and an address of the first authentication server, and the registration type identifier is used to indicate that current secure access of the terminal is secure access using a fast re-authentication procedure; receiving, by the first authentication server, a registration success indication from the home subscriber server; and sending, by the first authentication server, an access success indication to the terminal based on the registration success indication, wherein the receiving the registration success indication is performed if: determining, by the home subscriber server, based on the identifier of the terminal that an address of an authentication server corresponding to the terminal is not stored; or determining, by the home subscriber server, based on the identifier of the terminal, that the address of the first authentication server is stored. determining, by the home subscriber server, based on the identifier of the terminal that an address of an authentication server corresponding to the terminal is not stored; or determining, by the home subscriber server, based on the identifier of the terminal, that the address of the first authentication server is stored.