Abstract: In order to solve and reduce the impact pressure phenomenon caused by the failure of near-vertical roof rock in the mining process of the coal seam, in view of the danger of the slope rock, the craft lane has been constructed inside the rock, and the high pressure water injection method was used to weaken the rock layer. In the engineering, the microseismic monitoring and the PASAT-M detection method were used to observe and statistics the weakening effect. The results show that high-pressure water injection changes the internal structure of rock mass and reduces the initial strength of rock mass. Microseismic monitoring revealed that the number of high-energy events decreased, the low energy events increased, the energy accumulation decreased and the impact risk decreased. The PASAT-M detections show that the peak of high stress zone in rock mass decreases and the peak of low stress zone increases, but the overall stress concentration coefficient decreases. Water injection softening engineering has obvious effect on reducing stress concentration of vertical rock layers, and can effectively mitigate or prevent the impact of vertical rock formations.