An entity bidirectional-identification method for supporting fast handoff involves three security elements, which includes two identification elements A and B and a trusted third party (TP). All identification entities of a same element share a public key certification or own a same public key. When any identification entity in identification element A and any identification entity in identification element B need to identify each other, if identification protocol has never been operated between the two identification elements that they belong to respectively, the whole identification protocol process will be operated; otherwise, interaction of identification protocol will be acted only between the two identification entities. Application of the present invention not only centralizes management of public key and simplifies protocol operation condition, but also utilizes the concept of security domain so as to reduce management complexity of public key, shorten identification time and satisfy fast handoff requirements on the premises of guaranteeing security characteristics such as one key for every pair of identification entities, one secret key for every identification and forward secrecy.