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, a first virtual forwarding device and a 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.