A radio link control, RLC, data packet offloading method, comprising: Receiving, by a first base station, an RLC data packet request message sent by a second base station, characterized in that: the RLC data packet request message is used by the second base station to request, from the first base station, a first quantity of RLC data packets that are to be sent by the second base station to carrier aggregation, CA, user equipment, UE, by using a secondary cell; the RLC data packet request message is sent by the second base station to the first base station at a first moment; a time difference between the first moment and a second moment is T, and T is greater than or equal to 2t; the second moment is a moment at which the second base station sends RLC data packets of the first quantity to the UE; and t is a unidirectional transmission delay between the second base station and the first base station; determining, by the first base station according to the RLC data packet request message, a second quantity of RLC data packets that are to be sent by the first base station to the UE by using a primary cell in duration of T-t, wherein a start time of the duration of T-t is a moment at which the first base station receives the RLC data packet request message; allocating, by the first base station in ascending order of serial numbers of to-be-sent RLC data packets, first RLC data packets of the second quantity in the to-be-sent RLC data packets to the first base station, and allocating, starting from a first RLC data packet whose serial number follows serial numbers of the first RLC data packets of the second quantity, the RLC data packets of the first quantity to the second base station; and sending, by the first base station, the RLC data packets of the first quantity to the second base station. Receiving, by a first base station, an RLC data packet request message sent by a second base station, characterized in that: the RLC data packet request message is used by the second base station to request, from the first base station, a first quantity of RLC data packets that are to be sent by the second base station to carrier aggregation, CA, user equipment, UE, by using a secondary cell; the RLC data packet request message is sent by the second base station to the first base station at a first moment; a time difference between the first moment and a second moment is T, and T is greater than or equal to 2t; the second moment is a moment at which the second base station sends RLC data packets of the first quantity to the UE; and t is a unidirectional transmission delay between the second base station and the first base station; determining, by the first base station according to the RLC data packet request message, a second quantity of RLC data packets that are to be sent by the first base station to the UE by using a primary cell in duration of T-t, wherein a start time of the duration of T-t is a moment at which the first base station receives the RLC data packet request message; allocating, by the first base station in ascending order of serial numbers of to-be-sent RLC data packets, first RLC data packets of the second quantity in the to-be-sent RLC data packets to the first base station, and allocating, starting from a first RLC data packet whose serial number follows serial numbers of the first RLC data packets of the second quantity, the RLC data packets of the first quantity to the second base station; and sending, by the first base station, the RLC data packets of the first quantity to the second base station.