A network address translation method for when a private network address of user equipment UE changes, wherein the private network address of the UE changes when the UE has accessed a current wireless software defined network SDN and an allocated private network address of the UE is changed, wherein an interface is disposed between a network address translation device and a controller, and the method comprises: receiving, by the network address translation device through the interface, a configuration message sent by the controller, wherein the configuration message comprises a pre-update private network address of the user equipment UE and a current private network address of the UE upon the configuration message comprising the pre-update private network address of the UE and the current private network address of the UE, updating, in a network address translation rule, the pre-update private network address of the UE to the current private network address of the UE; and performing address translation, by the network address translation device, on a packet of the UE according to the network address translation rule; before the receiving, by the network address translation device through the interface, a configuration message sent by the controller, further comprising: when the network address translation device receives the packet sent by the UE and does not find, in the network address translation rule, the network address mapping entry corresponding to the UE, sending a network address translation rule request message to the controller, wherein the request message comprises at least the current public network address of the UE; and wherein the updating, in a network address translation rule, the pre-update private network address of the UE to the current private network address of the UE comprises: querying, in the network address translation rule, the network address mapping entry corresponding to the UE; and updating, in the found network address mapping entry, the pre-update private network address of the UE to the current private network address of the UE. receiving, by the network address translation device through the interface, a configuration message sent by the controller, wherein the configuration message comprises a pre-update private network address of the user equipment UE and a current private network address of the UE upon the configuration message comprising the pre-update private network address of the UE and the current private network address of the UE, updating, in a network address translation rule, the pre-update private network address of the UE to the current private network address of the UE; and performing address translation, by the network address translation device, on a packet of the UE according to the network address translation rule; before the receiving, by the network address translation device through the interface, a configuration message sent by the controller, further comprising: when the network address translation device receives the packet sent by the UE and does not find, in the network address translation rule, the network address mapping entry corresponding to the UE, sending a network address translation rule request message to the controller, wherein the request message comprises at least the current public network address of the UE; and wherein the updating, in a network address translation rule, the pre-update private network address of the UE to the current private network address of the UE comprises: querying, in the network address translation rule, the network address mapping entry corresponding to the UE; and updating, in the found network address mapping entry, the pre-update private network address of the UE to the current private network address of the UE. when the network address translation device receives the packet sent by the UE and does not find, in the network address translation rule, the network address mapping entry corresponding to the UE, sending a network address translation rule request message to the controller, wherein the request message comprises at least the current public network address of the UE; and wherein the updating, in a network address translation rule, the pre-update private network address of the UE to the current private network address of the UE comprises: querying, in the network address translation rule, the network address mapping entry corresponding to the UE; and updating, in the found network address mapping entry, the pre-update private network address of the UE to the current private network address of the UE. querying, in the network address translation rule, the network address mapping entry corresponding to the UE; and updating, in the found network address mapping entry, the pre-update private network address of the UE to the current private network address of the UE.