Abstract: In order to determine the reasonable section coal pillar size of the impact ground pressure mine, taking the 21103 working face of the cucurbit coal mine as the research background, the theoretical method is used to calculate the width of the coal pillar limit equilibrium zone, starting from the two aspects of coal pillar stress and surrounding rock deformation. The numerical simulation calculations under different coal pillar widths were carried out, and the coal pillars of 21103 auxiliary transport roads were monitored by 4m, 6m, 8m, 10m, 12m, 14m, 16m, 18m, 20m, 22m and 24m. The width of the section coal pillar is 9.1~10.7m. The numerical simulation results show that the stress of the coal pillar increases first and then decreases with the increase of the width. The stress is the lowest at 5m and the highest at 15m. The displacement of the top, bottom and left side of the roadway is inversely proportional to the width of the coal pillar. The displacement of the right dam first increases and then decreases. When the coal pillar is 10m, the displacement is the largest. The simulation results of the comprehensive stress and surrounding rock deformation suggest the section coal pillar 5 -10m is suitable; the measured data analysis shows that the reasonable coal pillar width is 10-12m. Finally, the optimal width of the coal pillars in the cucurbit coal mine section is 10m.