A method of informing a network of a change of user equipment capability includes: receiving, by a network, a register request message carrying information of new user equipment capability to from a user equipment; analyzing, by the network, the register request message, and storing the information of new user equipment capability for reference by subsequent establishment of a session; stopping a current registration timer on the server side set for the user equipment; initiating a new registration timer on the server side for the user equipment; and sending a response message carrying information of the new registration timer on the server side to the user equipment so as to reset a registration timer on the user side based on information of the new registration timer on the server side in the response message. The capability change is informed to the network in time.