A network handover method, a communications system, and relevant devices are provided, so as to implement handover between a Wireless Fidelity (WiFi) network and a Worldwide Interoperability for Microwave Access (WiMAX) network. The method specifically includes the following steps. A user terminal determines a target network access point (AP) and acquires a tunnel destination address. A signaling transmission tunnel between the user terminal and the target network AP is established through a current network according to the tunnel destination address. The user terminal executes a network access operation with the target network AP through the signaling transmission tunnel. The communications system and the relevant devices are further provided. Thus, the handover between the WiFi network and the WiMAX network can be implemented.