A mobility management method performed by a serving GPRS support node or a mobility management entity, the method comprising: obtaining subscription data of a terminal, wherein the subscription data carries periodic routing area update or tracking area update setting information; obtaining a periodic routing area update or tracking area update timer of the terminal according to the periodic routing area update or tracking area update setting information; sending the periodic routing area update or tracking area update timer of the terminal to the terminal; and setting a value, which is a little longer than the periodic routing area update or tracking area update timer of the terminal, as a mobile reachable timer for monitoring a periodic routing area update or tracking area update of the terminal; wherein the sending the periodic routing area update or tracking area update timer of the terminal to the terminal comprises: sending an Attach Accept message to the terminal, wherein the Attach Accept message carries the periodic routing area update or tracking area update timer of the terminal; or sending a routing area update or tracking area update Accept message to the terminal, wherein the routing area update or tracking area update Accept message carries the periodic routing area update or tracking area update timer of the terminal; the method characterized in that: when the periodic routing area update or tracking area update timer of the terminal is sent to the terminal, a binary code of a value unit of the timer comprises: 011, or 100, or 101, or 110, and the value unit is larger than 6 minutes. obtaining subscription data of a terminal, wherein the subscription data carries periodic routing area update or tracking area update setting information; obtaining a periodic routing area update or tracking area update timer of the terminal according to the periodic routing area update or tracking area update setting information; sending the periodic routing area update or tracking area update timer of the terminal to the terminal; and setting a value, which is a little longer than the periodic routing area update or tracking area update timer of the terminal, as a mobile reachable timer for monitoring a periodic routing area update or tracking area update of the terminal; wherein the sending the periodic routing area update or tracking area update timer of the terminal to the terminal comprises: sending an Attach Accept message to the terminal, wherein the Attach Accept message carries the periodic routing area update or tracking area update timer of the terminal; or sending a routing area update or tracking area update Accept message to the terminal, wherein the routing area update or tracking area update Accept message carries the periodic routing area update or tracking area update timer of the terminal; the method characterized in that: when the periodic routing area update or tracking area update timer of the terminal is sent to the terminal, a binary code of a value unit of the timer comprises: 011, or 100, or 101, or 110, and the value unit is larger than 6 minutes. sending an Attach Accept message to the terminal, wherein the Attach Accept message carries the periodic routing area update or tracking area update timer of the terminal; or sending a routing area update or tracking area update Accept message to the terminal, wherein the routing area update or tracking area update Accept message carries the periodic routing area update or tracking area update timer of the terminal; the method characterized in that: when the periodic routing area update or tracking area update timer of the terminal is sent to the terminal, a binary code of a value unit of the timer comprises: 011, or 100, or 101, or 110, and the value unit is larger than 6 minutes.