Abstract: Groundwater level rebounded after coal mines abandoned, and the changes of groundwater level probably damaged the waterproof pillars between coal mines, which brought a great water inrush threat for the adjacent production mine. Based on the analysis of components of waterproof pillars and lateral pressure forced on pillars, it obtained the maximum water pressure calculation formula of waterproof pillar destruction. Through establishing the theory model of typical abandoned mines, it carried out simulation calculation for groundwater level rebound to get the data of water level change. With the formula, it obtained the critical water level and possible damage time of waterproof pillars in this model, and analyzed the degree of water inrush threat for adjacent mine.