Abstract: In order to ensure the reasonable width of section coal pillar,the FLAC^3D numerical simulation software combined with the specific conditions of a mine has been adopted.The stress intensity and plastic destruction under different width of coal pillar have been analyzed.The results show that the coal pillar still has better carrying capacity while the width of coal pillar reduces from 20 m to 13 m,but when the width of coal pillar is less than 13 m,the coal pillar loses its carrying capacity.Finally,the reasonable width of coal pillar is 13 m.