A method for verifying the validity of a user, applied to 3rd generation wireless communication technology in which a network application function, NAF, verifies the validity of a user by means of an authentication architecture, the method comprising: receiving an application request message containing a transaction identifier, TID, from a user equipment, UE; checking whether there is TID information stored in the NAF; if the TID information is found, determining whether the TID has expired based on a preset term of validity for the TID, if the TID has expired, instructing the UE to connect to a bootstrapping server function BSF, to perform a bootstrapping authentication; if the TID information is not found, the NAF sends, to the BSF, a TID inquiring message containing an identity of the NAF; if the TID inquired by the NAF is found, the BSF returns, to the NAF, a response message of success containing the information of the TID and the term of validity of the TID wherein said term of validity is determined by the BSF based on the identity or name of the NAF and on profile information of the UE, and the method further comprises: storing the TID information and the term of validity of the TID in the response message and making normal communications with the UE; or if the TID information inquired by the NAF is not found, the BSF returns to the NAF a response message of failure, and the method further comprises: instructing the UE to perform a bootstrapping authentication with the BSF. receiving an application request message containing a transaction identifier, TID, from a user equipment, UE; checking whether there is TID information stored in the NAF; if the TID information is found, determining whether the TID has expired based on a preset term of validity for the TID, if the TID has expired, instructing the UE to connect to a bootstrapping server function BSF, to perform a bootstrapping authentication; if the TID information is found, determining whether the TID has expired based on a preset term of validity for the TID, if the TID has expired, instructing the UE to connect to a bootstrapping server function BSF, to perform a bootstrapping authentication; if the TID information is not found, the NAF sends, to the BSF, a TID inquiring message containing an identity of the NAF; if the TID inquired by the NAF is found, the BSF returns, to the NAF, a response message of success containing the information of the TID and the term of validity of the TID wherein said term of validity is determined by the BSF based on the identity or name of the NAF and on profile information of the UE, and the method further comprises: storing the TID information and the term of validity of the TID in the response message and making normal communications with the UE; or if the TID information inquired by the NAF is not found, the BSF returns to the NAF a response message of failure, and the method further comprises: instructing the UE to perform a bootstrapping authentication with the BSF. if the TID inquired by the NAF is found, the BSF returns, to the NAF, a response message of success containing the information of the TID and the term of validity of the TID wherein said term of validity is determined by the BSF based on the identity or name of the NAF and on profile information of the UE, and the method further comprises: storing the TID information and the term of validity of the TID in the response message and making normal communications with the UE; or storing the TID information and the term of validity of the TID in the response message and making normal communications with the UE; or if the TID information inquired by the NAF is not found, the BSF returns to the NAF a response message of failure, and the method further comprises: instructing the UE to perform a bootstrapping authentication with the BSF. instructing the UE to perform a bootstrapping authentication with the BSF.