The invention discloses a self-adaptive adjustment method of an ARQ (automatic repeat request) parameter of an MAC (media access control) layer. The self-adaptive adjustment method comprises the steps: S1. dividing the network condition into three conditions of good, medium and poor according to the ratio of NACK (negative acknowledgement) and ACK (acknowledgment) received by a transmitting terminal; S2. setting the ARQ parameter according to the good condition of the network by the transmitting terminal according to a modulation encoding mode of a physical layer and service quality QoS priority while building connection, and transmitting a DSA-REQ request to build a new service flow; and S3. starting a timer Tmonitor by the transmitting terminal in a data transmission process, counting the quantity of the NACK and the ACK within a preset time interval, estimating the network condition according to the ratio of the NACK and the ACK, and negotiating the ARQ parameter again through DSC if the network condition or the modulation encoding mode of the physical layer changes. According to the method adopted by the invention, sudden drop of the performance under the condition that the ARQ parameter and the network condition or the modulation encoding mode of the physical layer are mismatched can be avoided and the throughput of the MAC layer is improved, so that the performance of the overall network achieves the optimal state.