A method for triggering an IMS (IP Multimedia Subsystem) registration in the IMS, includes sending, by network side or a user who initiates the triggering, an IMS registration triggering indication message to a user who needs the IMS registration, to prompt the user who needs the IMS registration to initiate the IMS registration to the IMS; according to the IMS registration triggering indication message, trigging the user who needs the IMS registration to initiate the IMS registration to the IMS. Since the network side or the user who initiates the triggering triggers the IMS registration for the user who needs the IMS registration, the problem that the SIP messages may not be issued to the user who needs the IMS registration and the IMS session may not be performed because the user who needs the IMS registration does not register in the IMS during the IMS session, can be avoided.