Abstract: In view of the fact that under special geological conditions, the effect of changing mining height and increasing support resistance is not obvious in maintaining the stability of coal wall in large mining height working face, the stability of coal wall is studied from the angle of improving coal strength. Based on Mohr-Coulomb criterion, the stability of coal wall in high mining face is theoretically analyzed, and the relationship between coal strength and stress of coal wall is revealed. The failure law of coal wall stability under different coal strength is summarized by numerical simulation. Finally, the deformation and failure of coal wall under different coal strength are analyzed intuitively through similar simulation experiments. The results show that both the tensile and shear failure of coal wall are related to the physical and mechanical properties of coal body. With the increase of coal body strength, the stability of coal wall is higher, and the increase of coal body strength has a significant impact on the stability of coal wall. In similar simulation experiments, when cohesion increases by 1 MPa, the critical pressure of coal wall failure increases by 1.64 MPa, and the failure height decreases. 1.7m, the damage depth is reduced by 0.7m.