A network side device, configured to control a bearer handover, wherein the network side device belongs to a wireless communications system, wherein the system further comprises a source base station and a target base station, and at least some of all bearers between user equipment and the source base station need to be handed over from the source base station to the target base station, and the network side device comprises: a receiving unit, configured to receive a bearer handover message; a processing unit, configured to determine, according to the bearer handover message, a bearer needing to be handed over in all the bearers; and a sending unit, configured to send an end marker message to the source base station only for the bearer needing to be handed over; wherein the network side device is a serving gateway, SGW, characterized in that the receiving unit configured to receive a bearer handover message comprises: a receiving unit of the SGW, configured to receive at least one bearer modification request message sent by a mobility management entity, MME, wherein bearer contexts comprised in the at least one bearer modification request message correspond to all the bearers; the processing unit configured to determine, according to the bearer handover message, a bearer needing to be handed over in all the bearers, comprises:a processing unit of the SGW, configured to determine, according to the bearer contexts in the at least one bearer modification request message, the bearer needing to be handed over; and the sending unit, configured to send an end marker message only for the bearer needing to be handed over to the source base station comprises: a sending unit of the SGW, configured to send the End Marker message to the source base station only for the bearer needing to be handed over; wherein the processing unit of the SGW is configured to determine, according to the bearer contexts in the at least one bearer modification request message, the bearer needing to be handed over comprises: being configured to match fully qualified tunnel endpoint identifiers, F-TEIDs, in the bearer contexts in the at least one bearer modification request message with F-TEIDs in bearer contexts that are currently stored by the SGW, and when an F-TEID of a bearer is changed, determine that the bearer is a bearer needing to be handed over. a receiving unit, configured to receive a bearer handover message; a processing unit, configured to determine, according to the bearer handover message, a bearer needing to be handed over in all the bearers; and a sending unit, configured to send an end marker message to the source base station only for the bearer needing to be handed over; wherein the network side device is a serving gateway, SGW, characterized in that the receiving unit configured to receive a bearer handover message comprises: a receiving unit of the SGW, configured to receive at least one bearer modification request message sent by a mobility management entity, MME, wherein bearer contexts comprised in the at least one bearer modification request message correspond to all the bearers; the processing unit configured to determine, according to the bearer handover message, a bearer needing to be handed over in all the bearers, comprises:a processing unit of the SGW, configured to determine, according to the bearer contexts in the at least one bearer modification request message, the bearer needing to be handed over; and the sending unit, configured to send an end marker message only for the bearer needing to be handed over to the source base station comprises: a sending unit of the SGW, configured to send the End Marker message to the source base station only for the bearer needing to be handed over; wherein the processing unit of the SGW is configured to determine, according to the bearer contexts in the at least one bearer modification request message, the bearer needing to be handed over comprises: being configured to match fully qualified tunnel endpoint identifiers, F-TEIDs, in the bearer contexts in the at least one bearer modification request message with F-TEIDs in bearer contexts that are currently stored by the SGW, and when an F-TEID of a bearer is changed, determine that the bearer is a bearer needing to be handed over.