This application provides a network handover method and an apparatus. Before a terminal device is handed over from a first network to a second network, the terminal device sets up a first tunnel to a first interworking device, where a communication identifier, of the terminal device, in the first tunnel is a first identifier the first identifier is an identifier used in the first network by the terminal device, and the first interworking device is an interface device in the first network and oriented toward a network other than the first network. After the terminal device is handed over from the first network to the second network, the terminal device sends an update request to the first interworking device, where the update request to update the communication identifier to a second identifier, and the second identifier is an identifier used in the second network by the terminal device.