Abstract: On the basis of the analysis of water jet rock breaking and antireflection, WSZ16/45-200 type gas extraction hole hydraulic rig and corresponding water jet nozzles were developed, the technology idea of piecewise flushing in-continuous flushing out was proposed, and the interval theory equation of the water jet continuous flushing was determined. The uncovering coal test in 27021 bottom return air pumping lane of Zhongmacun Coal Mine showed that the coal output was 1.3 to 1.8 times of the quantity of conventional hydraulic flushing by using gas extraction hole hydraulic rig, after flushing, the coal seam gas content decreased from 13.32 m³/t to 7.69 m³/t, △h₂ was 0 to 137.2 Pa during uncovering coal,S was 1.3 to 2.4 kg/m, the maximum of q was 3.48 L/min, thus the rock cross-cut was uncovered successfully.