The embodiment of the invention discloses a security authentication method and a terminal. The method comprises the steps of determining a security level of terminal authentication according to usage scenario of the terminal, wherein the usage scenario comprises the distance between the terminal and a user or an application type corresponding to the terminal authentication; and starting different security authentication mechanisms according to the security level of the terminal authentication. The terminal comprises a determining unit for determining the security level of the terminal authentication according to the usage scenario of the terminal, wherein the usage scenario comprises the distance between the terminal and the user or the application type corresponding to the terminal authentication; and an authentication unit for starting different security authentication mechanisms according to the security level of the terminal authentication. According to the method and the terminal provided by the embodiment of the invention, the information security of the user can be improved, and the information security demand of the user can be satisfied.