The invention discloses a method and a device for identity authentication. The method comprises the following steps: acquiring a request indicating data transfer sent by a first user terminal; acquiring the current location information of the first user terminal according to the request; acquiring the information of a second user terminal logging in at a location indicated by the location information according to the location information; and accepting the request indicating data transfer sent by the first user terminal when determining that the second user terminal is a credible social user terminal of the first user terminal at the location according to the information of the second user terminal. According to the embodiments of the invention, risks and property loss caused by mobile payment are avoided, and identity authentication is made safer and more convenient.