Abstract: Based on the coal wall mechanics model, the relationship between the front abutment pressure of the working face and the compression angle of the coal seam is analyzed. Combining with the actual situation of 4322 working face in Chengzhuang Coal Mine, the stress of coal seam in fully mechanized coal mining face with large mining height is studied. The stress on the coal wall is calculated to be 15.0 MPa, the peak value of the front abutment pressure of the working face is 22.6 MPa, and the width of limit equilibrium zone of the coal wall is 16.4 m. The numerical simulation software FLAC^3D is used to solve the stress of coal wall after mining 150 m to verify the theoretical calculation results. By analyzing the plastic breaking range of the central and end coal walls of the working face, the stability of coal wall in 4322 working face is studied. It is shown that the coal wall at both ends of the working face is easier to rib spalling than the middle coal wall. According to the law of the front abutment pressure of the working face and the area of the plastic zone in front of the coal wall, the mechanism of coal wall rib spalling in the fully mechanized coal mining face is studied, and the measures are taken to prevent the coal wall rib spalling.