Abstract: Taking a mine as the research background, we study reasonable width of coal pillar during 6-6^# coal seam mining in S₁ and S₂ sections, based on Mohr coulomb criterion and SMP criterion, we calculate the reasonable width of sectional coal pillar and adopt FLAC^3D numerical simulation method to study characteristics of stress distribution in S₂ coal under the different distances after mining S₁ section in 6-6^# coal seam, and horizontal stress and vertical stress of coal pillar and non-plastic damage width of coal pillar, and roadway surrounding rock displacement situation of S₂ section under different width of sectional coal pillar （6 m, 8 m, 10 m and 12 m, 14 m, 16 m and 18 m）; by studying, the final mine reasonable width of sectional coal pillar of 6-6^# coal seam should be 11 m to 12 m. The calculated coal pillar widths by Mohr coulomb criterion and SMP criterion are compared with the simulation results, we find that the simulation results are close to the results by SMP criterion.