A method for implementing network virtualization, and a related apparatus and a communications system are provided. The method for implementing network virtualization may include: receiving, by an SDN controller, a virtual network creation request that carries virtual network topology information; creating a virtual network in response to the virtual network creation request; establishing, by the SDN controller, a device mapping relationship; establishing, by the SDN controller, a port mapping relationship; allocating, by the SDN controller, a virtual SDN controller to the virtual network; and registering, by the SDN controller, the first virtual forwarding device and the second virtual forwarding device with the virtual SDN controller. Technical solutions of embodiments of the present invention help to improve networking flexibility, reduce service costs, and shorten a service deployment period.