Abstract: Based on the theory of elasticity, mining floor stress mechanical model was established along the coal seam mining, the size of shear stress in coal floor was calculated in the process of coal mining. Based on stope conditions of Wusuotun Mine 16105 working face, we use numerical simulation software FLAC^3D to conduct fluid-solid coupling numerical simulation of stress distribution in coal floor. The research shows that: after coal seam mining, vertical stress contours of gob floor is “elliptic type” distribution, gob floor vertical stress decreases rapidly at first and then increases slowly toward the deep floor, and increase rate tends to small. Mining floor shear stress distribution is roughly “bubble type” distribution on both sides of the working face, when advancing distance equals to working face inclined length, floor shear stress reaches to peak of 12 MPa, floor shear failure is most severe at this time. Simulation calculation shows that the maximum damage depth of 16105 face floor is 15 m.