Abstract: In order to study the influence of the coal pillar left in the upper protection layer on the protection effect of the protected layer, the 4 m coal pillar left at the lower side of Ⅵ15-23160 connecting roadway and Ⅵ15-23140, Ⅵ15-23160 and Ⅵ16.17-23140 working faces in Pingmei No. 4 Mine are taken as the research objects. The research is carried out by combining numerical simulation and field measurement. The research results are as follows: the coal pillar is compacted along the negative direction of the z axis, with a cumulative maximum displacement of 0.289 m; the coal walls on both sides of the coal pillar move in different directions along the x axis, the upper wall is along the negative direction of the x axis, the lower wall is along the positive direction of the x axis, and the cumulative displacement is 0.055 m and 0.156 m, respectively; the mining activities of Ⅵ15-23160 working face have the most significant impact on the displacement of the coal pillar, and the largest remaining coal pillar is 0.59 m, which is 1.01 m lower than the original coal pillar height; the residual gas content of deep coal has the same change trend as the amount of drill cuttings. The maximum residual coal seam gas content is 2.63 m3/t, and the coal seam gas release rate remains above 50%, and the maximum amount of cuts is 3.7 kg/m. The coal seam gas in the area affected by the residual coal pillars is well released without obvious stress concentration. The 4 m coal pillar left by protective layer mining can achieve continuous protection.