A method performed by an access network device in a 4G LTE network for returning a terminal device to 5G NR network after a fall back from the 5G NR network to the 4G LTE network, comprising the following steps: receiving, by the access network device, channel quality status information, wherein the channel quality status information is used to reflect the channel quality of the 5G NR network; and determining, by the access network device, when determining that a first service of the terminal device is ended, whether to switch a service network of the terminal device from the 4G LTE network to the 5G NR network according to the channel quality status information, wherein the channel quality status information is a measurement result report sent by the terminal device, and wherein before the access network device receives a measurement result report sent by the terminal device, the method further comprises: sending, by the access network device, first indication information to the terminal device, wherein the first indication information is used to instruct the terminal device to send the measurement result report to the access network device, wherein the sending, by the access network device, the first indication information to the terminal device, comprises: sending, by the access network device, a release command to the terminal device, wherein the release command is used to instruct the terminal device to release the first service, and the release command comprises the first indication information, characterized in that the access network device receiving a measurement result report sent by the terminal device comprises: receiving, by the access network device, a response message to the release command which is sent by the terminal device, wherein the response message comprises the measurement result report. receiving, by the access network device, channel quality status information, wherein the channel quality status information is used to reflect the channel quality of the 5G NR network; and determining, by the access network device, when determining that a first service of the terminal device is ended, whether to switch a service network of the terminal device from the 4G LTE network to the 5G NR network according to the channel quality status information, wherein the channel quality status information is a measurement result report sent by the terminal device, and wherein before the access network device receives a measurement result report sent by the terminal device, the method further comprises: sending, by the access network device, first indication information to the terminal device, wherein the first indication information is used to instruct the terminal device to send the measurement result report to the access network device, wherein the sending, by the access network device, the first indication information to the terminal device, comprises: sending, by the access network device, a release command to the terminal device, wherein the release command is used to instruct the terminal device to release the first service, and the release command comprises the first indication information, characterized in that the access network device receiving a measurement result report sent by the terminal device comprises: receiving, by the access network device, a response message to the release command which is sent by the terminal device, wherein the response message comprises the measurement result report. sending, by the access network device, first indication information to the terminal device, wherein the first indication information is used to instruct the terminal device to send the measurement result report to the access network device, wherein the sending, by the access network device, the first indication information to the terminal device, comprises: sending, by the access network device, a release command to the terminal device, wherein the release command is used to instruct the terminal device to release the first service, and the release command comprises the first indication information, characterized in that the access network device receiving a measurement result report sent by the terminal device comprises: receiving, by the access network device, a response message to the release command which is sent by the terminal device, wherein the response message comprises the measurement result report. sending, by the access network device, a release command to the terminal device, wherein the release command is used to instruct the terminal device to release the first service, and the release command comprises the first indication information, characterized in that the access network device receiving a measurement result report sent by the terminal device comprises: receiving, by the access network device, a response message to the release command which is sent by the terminal device, wherein the response message comprises the measurement result report.