Abstract: Based on retaining the section coal pillar in Yangzhuang Coal Mine, the numerical simulation method is used to analyze the main stress difference, plastic zone, supporting force and the displacement evolution characteristics of surrounding rock with the change of coal pillar width. The “saddle” width of the main stress difference curve is in good agreement with the evolution characteristics of non-plastic zone of coal pillar. The main stress difference, the bolt support force, the deformation of surrounding rock, and the evolution characteristics of the plastic zone of coal pillar can effectively characterize the stability. When the width of coal pillar is 6 m, the plastic zone has basically passed through, and the peak value of the principal stress difference is the highest, which makes the stability of the coal pillar poorest. The reasonable width is from 8 m to 10 m. The result of application shows that the deformation of surrounding rock can be effectively maintained, and the requirements of the mine can be met when the width is 8 m.