The present disclosure provides an identity information authentication method and related device and system. The identity information authentication method comprises: receiving an authentication application sent by the service terminal; sending first encrypted information to said service terminal, such that the service terminal forwards the first encrypted information to the authentication server, and the authentication server analyzes and authenticates the first encrypted information; receiving second encrypted information fed back by said authentication server, said second encrypted information being generated by the authentication server after authenticating the first encrypted information as legitimate, and then being sent to the user terminal by the authentication server by means of the service terminal; analyzing and authenticating the second encrypted information; if said second encrypted information is authenticated to be legitimate, then obtaining a biological identifier of the user, and sending the
