Abstract: Based on the geological and hydro-geological conditions of working face of No.2 coal seam in Shanxi Longkuang Pandao Coal Corporation, the numerical simulation software FLAC^3D with changeable dip angle of coal seam is adopted to simulate the whole process of mining-induced damage of rock mass in the coal seam floor and study and analyze the change characteristics of floor mining-induced damage under the geological conditions of different dip angles of coal seam. The study results showed that with the increase of coal seam dip angles, the maximum depth of the coal seam floor damage showed a decreasing trend after the first increase, while it will reach the maximum damage depth when the dip angle of coal seam is 30°. We combined theoretical calculation with numerical simulation to predict water inrush in the coal seam floor simultaneously.