A data packet retransmission method, wherein the method comprises: sending, by a radio link control RLC protocol entity of a transmit end, a target sequence number and a first data packet to a medium access control MAC entity of the transmit end, wherein the RLC entity of the transmit end is in an unacknowledged mode, and the target sequence number is a sequence number of the first data packet; recording, by the RLC entity of the transmit end, a quantity of times that the target sequence number is transmitted to the MAC entity of the transmit end at an RLC layer; when the RLC entity of the transmit end receives the target sequence number and a negative acknowledgement that are sent by the MAC entity of the transmit end, obtaining, by the RLC entity of the transmit end, the RLC layer transmission count corresponding to the target sequence number; and when the RLC entity of the transmit end determines that the RLC layer transmission count is less than an RLC layer transmission threshold, sending, by the RLC entity of the transmit end, a retransmission instruction based on the first data packet to the MAC entity of the transmit end, wherein before the sending, by the RLC entity of the transmit end, a retransmission instruction based on the first data packet to the MAC entity of the transmit end, the method further comprises: generating, by the RLC entity of the transmit end based on the target sequence number and a retransmission identifier, the retransmission instruction based on the first data packet, wherein the retransmission identifier is used to indicate the MAC entity of the transmit end to retransmit the first data packet corresponding to the target sequence number, and characterized in that the retransmission instruction includes the target sequence number and the retransmission identifier, and does not include the first data packet. sending, by a radio link control RLC protocol entity of a transmit end, a target sequence number and a first data packet to a medium access control MAC entity of the transmit end, wherein the RLC entity of the transmit end is in an unacknowledged mode, and the target sequence number is a sequence number of the first data packet; recording, by the RLC entity of the transmit end, a quantity of times that the target sequence number is transmitted to the MAC entity of the transmit end at an RLC layer; when the RLC entity of the transmit end receives the target sequence number and a negative acknowledgement that are sent by the MAC entity of the transmit end, obtaining, by the RLC entity of the transmit end, the RLC layer transmission count corresponding to the target sequence number; and when the RLC entity of the transmit end determines that the RLC layer transmission count is less than an RLC layer transmission threshold, sending, by the RLC entity of the transmit end, a retransmission instruction based on the first data packet to the MAC entity of the transmit end, wherein before the sending, by the RLC entity of the transmit end, a retransmission instruction based on the first data packet to the MAC entity of the transmit end, the method further comprises: generating, by the RLC entity of the transmit end based on the target sequence number and a retransmission identifier, the retransmission instruction based on the first data packet, wherein the retransmission identifier is used to indicate the MAC entity of the transmit end to retransmit the first data packet corresponding to the target sequence number, and characterized in that the retransmission instruction includes the target sequence number and the retransmission identifier, and does not include the first data packet. generating, by the RLC entity of the transmit end based on the target sequence number and a retransmission identifier, the retransmission instruction based on the first data packet, wherein the retransmission identifier is used to indicate the MAC entity of the transmit end to retransmit the first data packet corresponding to the target sequence number, and characterized in that the retransmission instruction includes the target sequence number and the retransmission identifier, and does not include the first data packet.