A secure access method performed by an authentication server includes receiving a first message from a non-3GPP access device. The method also includes performing fast re-authentication with the terminal when determining that fast re-authentication is allowed. The method further includes sending a second message to a home subscriber server. The second message carries a registration type identifier, an identifier of the terminal, and an address of the authentication server. The registration type identifier is used to indicate that current secure access of the terminal is secure access using a fast re-authentication procedure. The method additionally includes receiving a registration success indication from the home subscriber server. The method also includes sending an access success indication to the terminal based on the registration success indication.