A method includes after receiving a first non-access stratum (NAS) security mode command (SMC) message sent by an initial access and mobility management function (AMF), a user equipment (UE) stores a first NAS security context; the UE receives a second NAS SMC message sent by a second AMF, where the message carries indication information used to indicate the UE to use the first NAS security context; and the UE uses the first NAS security context as a current NAS security context based on the indication information. According to the method for mobility registration provided in this application, when receiving the second NAS SMC message sent by the second AMF, the UE uses the first NAS security context as the current NAS security context, and then processes the second NAS SMC message, so that the NAS security contexts on the UE and the second AMF are consistent.