The present invention relates to a wireless communication system. More specifically, the present invention relates to a method and a device for performing autonomous RLC retransmission in a wireless communication system, the method comprising: transmitting a RLC PDU to a RLC receiver on a first transmission opportunity; checking, by the RLC transmitter, whether a condition for performing a RLC PDU retransmission procedure is met or not, when the RLC PDU is transmitted to the RLC receiver on the first transmission opportunity; and re-transmitting, by the RLC transmitter, the RLC PDU during consecutive transmission opportunities following the first transmission opportunity if a condition is met.