The present invention provides an entity identification method, apparatus and system, and relates to: an entity A transmits an identification request message to an entity B, the identification request message includes the result SN1 of an XOR operation of a Pre-Shared Key (PSK) and the data from processing data N1 according to a first agreed rule, wherein data N1 is generated by entity A, and the PSK is a key shared by A and B; entity B receives the identification request message, performs an XOR operation on SN1 and PSK, performs a process according to a second agreed rule, then performs a process according to a third agreed rule, and then performs an XOR operation again with the PSK processed according to the third agreed rule and then processed according to a fourth rule to obtain SON1, and transmits SON1 through an identification response message to entity A.