Abstract: Improving coal mining rate is of great significance in resource utilization,and the small coal pillar retaining entry in inclined coal seam can greatly improve the mining rate,but at the same time it will bring about serious deformation of the entry and difficulties in support. In order to solve the deformation problem of small coal pillars in inclined coal seams,the small coal pillar in the 210303 working face of Renjiazhuang Coal Mine was taken as the research object. The structural mechanics analysis was used to obtain an instability critical line perpendicular to the coal seam roof and parallel to the entry direction,and the existence of this line was further verified by numerical simulation. The coal on both sides of this line moves in opposite directions,leading to entry instability. Based on the location of the instability critical line,the support design of the 210303 air entry was re-conducted. The length of the anchor rod was extended,the prestress of the anchor rod and the anchor cable was increased,and the coal on both sides of the instability critical line was strengthened into a whole.The surface displacement monitoring results of the entry show that the deformation of the surrounding rock in the 210303 air entry is small,and the entry support design is reasonable.