Coal pillar of 1303 working face in Liuwan Mine with width 18.6 m, the structure of coal pillar was affected by goaf water and mining influence. In order to get the stability feature of coal pillar, coal pillar physical model was set up by mechanical analysis, critical size of coal pillar plastic zone damaged by coal was studied. Distribution of plastic zone and stress characteristics in coal pillar mining and recovery was simulated, combined with Mechanical research and numerical calculation, Theoretical research value of coal pillar stability was got.