A switching method, comprising: sending, by a source access network device, a tunnel setup request message to a target access network device, in response to switching, determined by the source access network device, of a terminal device from a source control plane core network device to a target control plane core network device; receiving, by the source access network device, information of a data tunnel established by the target access network device according to the tunnel setup request message; and sending, by the source access network device, the information of the data tunnel to the terminal device, wherein the information of the data tunnel is used for data transmission between the terminal device and a user plane core network device, characterized in that the switching method further comprises: receiving, by the source access network device, uplink data sent by the terminal device to the target access network device and then forwarded by the target access network device through the data tunnel; and sending, by the source access network device, the uplink data to the user plane core network device, wherein the data tunnel is a tunnel between the source access network device and the target access network device, and is released by the target access network device in response to a switching completion message sent by the terminal device, wherein the source access network device and the target access network device are of different access network technology types, and the source control plane core network device and the target control plane core network device are core network devices in different communication systems. sending, by a source access network device, a tunnel setup request message to a target access network device, in response to switching, determined by the source access network device, of a terminal device from a source control plane core network device to a target control plane core network device; receiving, by the source access network device, information of a data tunnel established by the target access network device according to the tunnel setup request message; and sending, by the source access network device, the information of the data tunnel to the terminal device, wherein the information of the data tunnel is used for data transmission between the terminal device and a user plane core network device, characterized in that the switching method further comprises: receiving, by the source access network device, uplink data sent by the terminal device to the target access network device and then forwarded by the target access network device through the data tunnel; and sending, by the source access network device, the uplink data to the user plane core network device, wherein the data tunnel is a tunnel between the source access network device and the target access network device, and is released by the target access network device in response to a switching completion message sent by the terminal device, wherein the source access network device and the target access network device are of different access network technology types, and the source control plane core network device and the target control plane core network device are core network devices in different communication systems. receiving, by the source access network device, uplink data sent by the terminal device to the target access network device and then forwarded by the target access network device through the data tunnel; and sending, by the source access network device, the uplink data to the user plane core network device, wherein the data tunnel is a tunnel between the source access network device and the target access network device, and is released by the target access network device in response to a switching completion message sent by the terminal device, wherein the source access network device and the target access network device are of different access network technology types, and the source control plane core network device and the target control plane core network device are core network devices in different communication systems.