Abstract: According to the safety influence factor analysis of underground waterproof sealing wall of mine water storage and utilization in underground goaf, a safety assessment program with qualitative method and quantitative method based on strength of sealing wall itself and strength of surrounding rock and width of waterproof coal pillar and water properties and water pressure in goaf as appraisal unit is established. Based on the analysis of reasons that the calculation formula of bearing strength of cylindrical form sealing wall and wedge form sealing wall and inverted cut cone form sealing wall are not suitable for flat plate form sealing wall, the bearing strength calculation physical and mathematical model of flat plate form sealing wall is built. According to the actual parameter of underground water sealing wall in Lijiahao Coal Mine, based on both the calculated safety hydraulic head and safety width of waterproof coal pillar and the qualitative appraisal results, the safety performance of underground water sealing wall can meet the demand of mine water storage and utilization in underground goaf.