Abstract: Due to the more developed water system in Gaotouyao Coal Mine, once the coal mining face is connected with the surface water in the process of mining, it will cause major safety accidents. In order to prevent the coal mine flooding accidents, with the help of the experience formula method, analogy method and numerical simulation method, we determine the reasonable size of waterproof coal and rock pillar. At present, the first mining face under water is safe, which proves that the reasonable coal rock pillar setting and limit mining thickness can achieve the desired effect.