A location update method, comprising: receiving, by a home location registrar, an Update Location request from a mobile network switch, wherein the Update Location request comprises an operator identity of a first domain of a user equipment UE; determining, by the home location registrar, whether the operator identity of the first domain is the same as an operator identity of a second domain of the UE; and sending, by the home location registrar according to a determining result, an Update Location response used for accepting the Update Location request when the determining result indicates that the operator identity of the first domain is the same as the operator identity of the second domain of the UE, or rejecting the Update Location request when the determining result indicates that the operator identity of the first domain is different from the operator identity of the second domain of the UE, wherein the first domain is a circuit switched CS domain and the second domain is a packet switched PS domain, or the second domain is a CS domain and the first domain is a PS domain; characterized by: the determining, by the home location registrar, whether the operator identity of the first domain is the same as an operator identity of a second domain of the UE is performed when the home location registrar determines that the Update Location request comprises at least one of the following: an indication that the UE does not support one of a gateway core network GWCN or a multi-operator core network MOCN, an indication that the UE does not execute joint registration, and an indication that the UE does not execute joint location update. receiving, by a home location registrar, an Update Location request from a mobile network switch, wherein the Update Location request comprises an operator identity of a first domain of a user equipment UE; determining, by the home location registrar, whether the operator identity of the first domain is the same as an operator identity of a second domain of the UE; and sending, by the home location registrar according to a determining result, an Update Location response used for accepting the Update Location request when the determining result indicates that the operator identity of the first domain is the same as the operator identity of the second domain of the UE, or rejecting the Update Location request when the determining result indicates that the operator identity of the first domain is different from the operator identity of the second domain of the UE, wherein the first domain is a circuit switched CS domain and the second domain is a packet switched PS domain, or the second domain is a CS domain and the first domain is a PS domain; characterized by: the determining, by the home location registrar, whether the operator identity of the first domain is the same as an operator identity of a second domain of the UE is performed when the home location registrar determines that the Update Location request comprises at least one of the following: an indication that the UE does not support one of a gateway core network GWCN or a multi-operator core network MOCN, an indication that the UE does not execute joint registration, and an indication that the UE does not execute joint location update. the determining, by the home location registrar, whether the operator identity of the first domain is the same as an operator identity of a second domain of the UE is performed when the home location registrar determines that the Update Location request comprises at least one of the following: an indication that the UE does not support one of a gateway core network GWCN or a multi-operator core network MOCN, an indication that the UE does not execute joint registration, and an indication that the UE does not execute joint location update.