A method performed by a first base station, the first base station being a secondary node, SN, of a dual connectivity, wherein a second base station is a master node, MN, of the dual connectivity, wherein a user equipment is served by the first base station and the second base station within the workframe of the dual connectivity, the method comprising the steps of: • receiving (step 1201) a SN addition request message from the second base station, wherein the SN addition request message comprises: ∘ at least one Quality of Service flow identifier, QoS flow ID, of at least one QoS flow of the user equipment that the second base station requests the first base station to transmit, and at least one corresponding QoS parameter corresponding to the at least one QoS flow, wherein each QoS flow among the at least one QoS flow corresponds to a different QoS flow ID among the at least one QoS flow ID, and each QoS parameter among the at least one QoS parameter corresponds to a different QoS flow among the at least one QoS flow, and ∘ data radio bearer identifiers, DRB IDs, of all currently available DRBs, wherein each DRB ID among the DRB IDs of all currently available DRBs corresponds to a different DRB among the currently available DRBs; • determining, based on a radio resource management policy of the first base station and based on a network condition of the first base station, a QoS flow ID among the at least one QoS flow IDs as a QoS flow ID accepted by the first base station, • selecting a DRB ID based on the determined QoS flow ID, based on the QoS parameter of the determined QoS flow and based on the DRB IDs of the currently available DRBs, • determining, as a reconfigured mapping relationship, a mapping relationship between the accepted QoS flow ID and the selected DRB ID, wherein the DRB corresponding to the selected DRB ID in the reconfigured mapping relationship is an added DRB added to the first base station; • sending (step 1202) a SN addition request acknowledgement message to the second base station, wherein the SN addition request acknowledgement message comprises the accepted QoS flow ID; • receiving (step 1205) a SN reconfiguration completion message from the second base station, wherein the SN reconfiguration completion message is an Xn interface message or an X2 interface message between the first base station and the second base station. • receiving (step 1201) a SN addition request message from the second base station, wherein the SN addition request message comprises: ∘ at least one Quality of Service flow identifier, QoS flow ID, of at least one QoS flow of the user equipment that the second base station requests the first base station to transmit, and at least one corresponding QoS parameter corresponding to the at least one QoS flow, wherein each QoS flow among the at least one QoS flow corresponds to a different QoS flow ID among the at least one QoS flow ID, and each QoS parameter among the at least one QoS parameter corresponds to a different QoS flow among the at least one QoS flow, and ∘ data radio bearer identifiers, DRB IDs, of all currently available DRBs, wherein each DRB ID among the DRB IDs of all currently available DRBs corresponds to a different DRB among the currently available DRBs; ∘ at least one Quality of Service flow identifier, QoS flow ID, of at least one QoS flow of the user equipment that the second base station requests the first base station to transmit, and at least one corresponding QoS parameter corresponding to the at least one QoS flow, wherein each QoS flow among the at least one QoS flow corresponds to a different QoS flow ID among the at least one QoS flow ID, and each QoS parameter among the at least one QoS parameter corresponds to a different QoS flow among the at least one QoS flow, and ∘ data radio bearer identifiers, DRB IDs, of all currently available DRBs, wherein each DRB ID among the DRB IDs of all currently available DRBs corresponds to a different DRB among the currently available DRBs; • determining, based on a radio resource management policy of the first base station and based on a network condition of the first base station, a QoS flow ID among the at least one QoS flow IDs as a QoS flow ID accepted by the first base station, • selecting a DRB ID based on the determined QoS flow ID, based on the QoS parameter of the determined QoS flow and based on the DRB IDs of the currently available DRBs, • determining, as a reconfigured mapping relationship, a mapping relationship between the accepted QoS flow ID and the selected DRB ID, wherein the DRB corresponding to the selected DRB ID in the reconfigured mapping relationship is an added DRB added to the first base station; • sending (step 1202) a SN addition request acknowledgement message to the second base station, wherein the SN addition request acknowledgement message comprises the accepted QoS flow ID; • receiving (step 1205) a SN reconfiguration completion message from the second base station, wherein the SN reconfiguration completion message is an Xn interface message or an X2 interface message between the first base station and the second base station.