Abstract: Taking the stope conditions of No.2 coal seam in Shanxi Longkuang Pandao Coal Company as the engineering background, FLAC^3D is used to conduct numerical simulation of fluid-solid for floor failure features in the working face advancing process. The research shows that vertical stress of gob roof is “semi-elliptical” shape after coal seam mining. Vertical displacement of gob roof is “annular” distribution, and vertical displacement below gob roof within 10 m is greatly influenced by mining; gob floor plastic zone forms a roughly flat “bowl” failure pattern; rock mass in the middle of the gob floor is greatly influenced by horizontal stress, given priority to shear failure. The floor near the coal wall on both ends of gob roof is greatly influenced by abutment pressure, given priority to tensile failure.