A communication system for quality of service, QoS, control during a handover process, comprising a source base station and a target base station, wherein: the source base station is configured to send a handover request message to the target base station, wherein the handover request message comprises: information of QoS of a service of a terminal device, information of a radio bearer identifier in a source cell of the source base station, and a mapping relationship between a flow and a radio bearer in the source cell; the target base station is configured to determine to admit the mobile device and establish for the mobile device a radio bearer in a target cell of the target base station, wherein the radio bearer in the target cell is established according to the radio bearer in the source cell for the flow, and configure a mapping relationship between the flow and the radio bearer in the target cell; the target base station is configured to send, based on the handover request message received from the source base station, a handover acknowledgement message to the source base station; the source base station is configured to send an RRC configuration message to the terminal device, wherein the configuration message comprises configuration information configured by the target base station for the terminal device and includes the correspondence between a radio bearer of the terminal device in the target base station and a radio bearer in the source base station and the mapping relationship between a flow and a radio bearer in the target base station; the source base station is configured to send (1404, 1405), a data packet of the flow for the mobile device to the target base station through a tunnel between the target base station and the source base station, and the tunnel is established for the radio bearer in the source cell of the source base station; and, the target base station is configured to send (1404, 1405) the data packet of the flow on the radio bearer in the target cell to the mobile device, wherein the radio bearer in the target cell is established according to the radio bearer in the source cell. the source base station is configured to send a handover request message to the target base station, wherein the handover request message comprises: information of QoS of a service of a terminal device, information of a radio bearer identifier in a source cell of the source base station, and a mapping relationship between a flow and a radio bearer in the source cell; the target base station is configured to determine to admit the mobile device and establish for the mobile device a radio bearer in a target cell of the target base station, wherein the radio bearer in the target cell is established according to the radio bearer in the source cell for the flow, and configure a mapping relationship between the flow and the radio bearer in the target cell; the target base station is configured to send, based on the handover request message received from the source base station, a handover acknowledgement message to the source base station; the source base station is configured to send an RRC configuration message to the terminal device, wherein the configuration message comprises configuration information configured by the target base station for the terminal device and includes the correspondence between a radio bearer of the terminal device in the target base station and a radio bearer in the source base station and the mapping relationship between a flow and a radio bearer in the target base station; the source base station is configured to send (1404, 1405), a data packet of the flow for the mobile device to the target base station through a tunnel between the target base station and the source base station, and the tunnel is established for the radio bearer in the source cell of the source base station; and, the target base station is configured to send (1404, 1405) the data packet of the flow on the radio bearer in the target cell to the mobile device, wherein the radio bearer in the target cell is established according to the radio bearer in the source cell.