Abstract: Based on the hydrogeological conditions in Fangezhuang coal mine, the hydraulic model for rock mass in coal mining with confined water was constructed. The author applies coupling system of flow & solid in rock failure process analysis to simulate and study the whole process of the initiation of fractures, extension and formation of groundwater inrush pathway. With the analysis of damage distribution, stress and seepage field evolution, the process of the evolution from water-resisting strata to inrush pathway about the floor of complete mudstone under the condition of mining disturbance and hydraulic driving is clearly revealed, and the water rush pathways are determined. Furthermore, the effects of water inrush under different water pressures in sandstone are discussed. The results show that the water inrush of coal seam 12 depends on the pressure of water in sandstone. The water pressure has a positive correlation with water bursting coefficient in the conditions of mudstone thickness, with the increasing water pressure, water inrush becomes easier. This research provides theoretical basis for forecasting and prevention of water inrush from the floor of coal seam 12.