The invention discloses an identity using method, device and system based on main identity multiple authentication, and relates to the technical field of computers. One specific embodiment of the method comprises the steps of receiving a use request, and the use request indicates an application to be used by a user and a main identity of the user; determining an identity certificate associated with the main identity of the user; and sending the identity certificate of the user to the application, so that the user uses the application according to the identity certificate. According to the embodiment, a user does not need to switch application identities for multiple times to log in different applications, so that the login efficiency is improved, and the user experience is improved.