The invention discloses a method for processing illegal location update, which includes the following steps: a mobile station sends a location update request, and after the network side receives the location update request, it first judges whether the request is the first location update request, and if so, proceeds with legality Judgment, if it is legal, then carry out the normal location update process, if it is an illegal user, then mark and return a false location confirmation message to the mobile station. If it is not the first location update request, then query whether the user has been marked as an illegal user, if so, return a false location confirmation message to the mobile station, otherwise perform a normal location update process. The method can effectively limit the number of location update attempts frequently initiated by illegal users in the existing network, reduce unnecessary load of the existing network equipment, and ensure the safety of the existing network equipment operation.