Provided are a method, device and system for implementing address sharing. An address pool configured for unified management over IP addresses is configured on an AAA server; and the AAA server may allocate an IP address to a CGN device according to the configured address pool. By such a technology for implementing address sharing in the present disclosure, IP address resource sharing among CGN devices is implemented, so that problems about resource load sharing among the CGN devices may be solved, a sharing rate of IP address resources is increased, and resource optimization may be implemented; and moreover, in terms of IP address management, a more available platform is provided for an operating company. In addition, the IP addresses are managed by the AAA server in a unified manner, and then the address pool is not required to be configured on the CGN device, so that the CGN device may be started without any address pool.