Abstract: The goaf water burst is one of the main types of mine water disaster,the accurate exploration of water inrush points can effectively prevent water inrush in goaf.This paper introduced the layout of the observation hole of pressure water test in Xinzhi Coal Mine.The change process of the maximum damage depth and permeability of floor strata in coal floor was test and analyzed.The pressure water test of coal floor before and after mining showed that the permeability of the rock strata below the bottom is obviously decreased with excavating activities in the working face and water resisting ability has a gradual recovery trend.It was inferred that the area with unrestored water proof ability has higher probability of water inrush after mining,it can provide basis for the exploration of water inrush passage in post-harvest water treatment.