A network handover method, comprising: receiving, by a session management network element, a service request from an access management network element of a first network, wherein the service request is used to request a session management context of a terminal device from the session management network element, the service request includes first indication information used to indicate that the terminal device is handed over from the first network to a second network to set up a voice service, and the second indication information is used to indicate that the terminal device needs to return to the first network after the voice service ends, after receiving the service request, the session management network element obtains the first indication information and the second indication information; and then sending, by the session management network element, the first indication information and the second indication information directly to an access network device of the second network, such that the session management network element sends session management information to the access network device of the second network, the session management information is used to release the user plane tunnel of the voice service, and the session management information includes the first indication information and the second indication information, the session management network element sends the session management information to the access management network element of the second network, to enable the access management network element of the second network to transparently transmit the session management information to the access network device of the second network. receiving, by a session management network element, a service request from an access management network element of a first network, wherein the service request is used to request a session management context of a terminal device from the session management network element, the service request includes first indication information used to indicate that the terminal device is handed over from the first network to a second network to set up a voice service, and the second indication information is used to indicate that the terminal device needs to return to the first network after the voice service ends, after receiving the service request, the session management network element obtains the first indication information and the second indication information; and then sending, by the session management network element, the first indication information and the second indication information directly to an access network device of the second network, such that the session management network element sends session management information to the access network device of the second network, the session management information is used to release the user plane tunnel of the voice service, and the session management information includes the first indication information and the second indication information, the session management network element sends the session management information to the access management network element of the second network, to enable the access management network element of the second network to transparently transmit the session management information to the access network device of the second network.