Abstract: Affected by the soaking of goaf water, the reduced bearing capacity of section coal pillar is not conducive to disaster prevention and control. In order to study the equivalent width of section coal pillar in rock burst coal seam under water-rich conditions, taking the 4-2 302 working face of a coal mine as an example, stress distribution characteristics and evolution laws of section coal pillars under immersion and natural water content conditions were analyzed by theoretical calculation, numerical simulation and engineering practice. The theoretical calculation results indicate that compared to immersion conditions, the width of the naturally water-bearing coal pillar decreased by 5.66 m, the width of the plastic zone decreased by 2.69 m, and the width of the elastic core zone decreased by 3.53 m. Furthermore, through numerical simulation and comparative analysis of stress peaks and ranges of 36 m immersed coal pillar and 26 m, 28 m, 30 m, 32 m with non-immersed coal pillar, it was found that the stress distribution curves of 30 m non-immersed coal pillar was similar to that of 36 m immersed coal pillar.