Abstract: For the problems of the delimitation and influence of protection scope in lower protective coal seam mining, the finite element analysis software ANSYS is used to simulate the mining of the protective layer, and the stress and deformation laws of the protected coal layer perpendicular to the coal bedding surface are explored as the working surface of the protected coal layer advances; according to the protection criterion of mining stress and pressure relief and the protection criterion of coal seam deformation, the protection scope of the protected layer along the dip and strike is determined, and the influencing factors of the protection effect of the protected layer are analyzed. Through the analysis of the protective range of a coal mine, the upper pressure relief angle of protected coal seam inclination is 60.32°, and lower pressure relief angle of protected coal seam inclination is 43.86°. The pressure relief angle of strike presents non-uniform distribution in all the dip positions, the maximum pressure relief position is near the central strike, and the biggest pressure relief angle is 54.46°. By analyzing the influencing factors of protective effect of protective layer, it can be seen that when the inclination angle of coal seam is small, the discrimination criterion of mining stress is more conservative than that of strain criterion, and the protective angle of pressure relief is relatively safe.