A bidirectional entity authentication method based on the credible third party includes the steps that: entity A receives message 1 sent from entity B including the authentication parameters of said entity B, and sends message 2 to the credible third party TP, said message 2 including the authentication parameters of entity B and the authentication parameters of entity A; entity A receives message 3 sent from said credible third party TP, said message 3 including the checking result after checking that whether said entity A and entity B are legal based on said message 2 by said credible third party TP; entity A gets the authentication result of entity B after authenticating said message 3, and sends message 4 to said entity B to make entity B authenticating based on said message 4 and getting the authentication result of entity A. The invention simplifies the operation condition of the protocol, reduces the computing capability requirement of the authentication entity, and satisfies the high security requirement of the network device lack of resource.