Abstract: Using the theory of material mechanics and the practical occurrence in the Xintie Coal Mine face of Longmei Group, the paper makes corresponding simplification on the load of the overlying strata and the holding power of filling gangue based on the asymmetry of the coal seam and filling characteristics of the collapsed gangue at the lower parts of face, puts forward the mechanical model of warping and deformation and the deflection curve equation of the roof in the steeply inclined working face, and analyzes the relations of different positions of the biggest deflection point of the roof with different mining height and face length.