Abstract: Given the issue of instability in coal walls and the risk of coal and rock fragments "rout" are easy to occur over fault of working face, this study analyses the horizontal stress distribution on the coal wall of the 15106 working face in Wangyun Coal Mine. The coal seam was classified as primary and structural coal. By analyzing the distribution characteristics of horizontal stress on coal wall, the mechanical model of coal wall was established. the impact of cohesion between the wall guard plate, top and bottom plate, and horizontal stress on coal wall deflection was analyzed, and the criteria for coal wall stability were established. The results indicate that the horizontal stress distribution function form between fault tectonic coal and primary coal depends on parameter k₀. Coal wall stability depends on the bending stiffness, roof and floor pressure, and mining height. It has been proven through practical application that pre-grouting and overdraft through the fault significantly improve the flexural stiffness of the coal wall, which in turn enhances its stability.