In order to ensure the safety of ash water strip mining in the bottom plate of Zhengxing Coal Industry, the hydrogeological situation of the mine field was analyzed from three aspects: main mine water filling, water barrier water blocking performance and sudden water passage, and the safety evaluation of the incoming water hazard in the bottom plate was carried out using the sudden water coefficient method. The results showed that Zhengxing Coal Industry was subject to old goaf water and bottom plate ash water with pressure mining danger, especially under the influence of mining, the fracture zone conduction was serious, and the risk of water breakout further increased, the safety evaluation and prevention measures of Zhengxing Coal Industry were given.