Embodiments of the present invention disclose a method and a gateway device for managing an address resource, which relate to the field of Internet technologies and can maximally reduce horizontal traffic between gateway devices, thereby improving system performance. The method in the present invention includes: sending an address delegation request message to a management gateway device in a same gateway group, where the management gateway device is configured to manage an address pool(s) or an address in an address pool; receiving a response message sent by the management gateway device, where the response message includes a delegated address, and the delegated address is an address in the address pool(s) managed by the management gateway device; acquiring the delegated address in the response message; and allocating an address in the delegated address to a user terminal in a same user group. The present invention is used for managing the address resource.