The invention discloses an identity authentication method and an identity authentication device, which are used for reducing overhead of identity authentication for a server. The method comprises the following steps: acquiring to-be-authenticated biological characteristic information acquired by a first terminal, sending the to-be-authenticated biological characteristic information and the preset standard biological characteristic information to a plurality of second terminals for presentation, receiving a first judgment result returned from each second terminal, wherein the first judgment result is the judgment result of judging whether the to-be-authenticated biological characteristic information is identical to the standard biological characteristic information or not by a user of the second terminal; and according to the first judgment result, judging whether the to-be-authenticated biological characteristic information passes the identity authentication or not. Since whether the to-be-authenticated biological characteristic information is identical to the standard biological characteristic information or not is judged by the user of the second terminal instead of the server, the server only needs to judge whether the to-be-authenticated biological characteristic information passes the identity authentication or not according to the first judgment result returned back by the first second terminal, obviously, overhead of identity authentication is reduced for the server.