A data transmission method, comprising: obtaining, by a first access network device, a first message from a second access network device, wherein the first message requests context information of a terminal device; sending, by the first access network device, a first response message to the second access network device, wherein the first response message comprises the context information of the terminal device, wherein the context information of the terminal device includes protocol data unit, PDU, session resource information of the terminal device established in the first access network device; obtaining, by the first access network device, protocol data unit, PDU, service receiving information from the second access network device, wherein the PDU service receiving information comprises identifier information of a first PDU session accepted by the second access network device and/or identifier information of a second PDU session rejected by the second access network device, and the first PDU session and the second PDU session are PDU sessions of the terminal device established in the first access network device; and sending, by the first access network device, a data packet to the second access network device based on the PDU service receiving information, wherein the first access network device is a corresponding access network device of the terminal device before a re-establishment procedure, wherein the first access network device is an access network device to which the terminal device fails to be connected, and the second access network device is a corresponding access network device when the terminal device initiates the re-establishment procedure, wherein the second access network device is an access network device to which the terminal device requests to establish a connection. obtaining, by a first access network device, a first message from a second access network device, wherein the first message requests context information of a terminal device; sending, by the first access network device, a first response message to the second access network device, wherein the first response message comprises the context information of the terminal device, wherein the context information of the terminal device includes protocol data unit, PDU, session resource information of the terminal device established in the first access network device; obtaining, by the first access network device, protocol data unit, PDU, service receiving information from the second access network device, wherein the PDU service receiving information comprises identifier information of a first PDU session accepted by the second access network device and/or identifier information of a second PDU session rejected by the second access network device, and the first PDU session and the second PDU session are PDU sessions of the terminal device established in the first access network device; and sending, by the first access network device, a data packet to the second access network device based on the PDU service receiving information, wherein the first access network device is a corresponding access network device of the terminal device before a re-establishment procedure, wherein the first access network device is an access network device to which the terminal device fails to be connected, and the second access network device is a corresponding access network device when the terminal device initiates the re-establishment procedure, wherein the second access network device is an access network device to which the terminal device requests to establish a connection.