Abstract: Coal seam gas drainage is the main technical measure to solve coal mine gas disasters, and the failure of drilling blockage caused by instability collapse and coal slag accumulation seriously affects the gas drainage effect.In order to solve the above problems, based on the technical advantages of high pressure water jet in the aspects of hole breaking, hole penetrating and slag discharging, a light pneumatic hydraulic plug removal and repair equipment is developed.The hydraulic parameters of the system equipment are determined, including the system resistance loss, hydraulic coal rock breaking parameters and the structural parameters of the rotating nozzle.It realizes the dredging and unplugging effect on the blocked section of the drilling, forming an economical and efficient drilling repair technology for gas extraction.The application results in No.3 gas lane in the south 5th district of Shihao Coal Mine show that, 23 test drillings are drilled through the strata, and 91.3% of the drillings with significant effect after repair are completed.Within 45 d after the completion of repair, the average gas density and pure flow rate of a single hole are increased from 36% and 0.003 5 m³/min to 60% and 0.008 2 m³/min, which are increased by 67% and 134%, respectively.The effect of plug removal and repair is good, which effectively improves the utilization rate and drainage efficiency of the extraction drilling.