Abstract: The mining of Group A coal in Pan 'er Coal Mine in Huainan Mining area is seriously threatened by the high confined water of floor. In order to clearly understand the depth and development mechanism of floor failure in Group A coal mining process, based on FLAC3D numerical simulation and microseismic monitoring technology, the stress distribution and floor failure range of Group A coal mining face under mining disturbance were analyzed. According to the real-time monitoring data of microseismic in the process of mining, the cluster analysis of floor crushing concentration range is made by SPSS software. The research results show that the concentrated depth of floor failure zone is 23~30m, and the average floor failure depth is about 27m. In the floor fractured rock mass of the lower stratified mining face, there is a large concentration in the floor depth of 9~22m, and it is highly concentrated at 21m below the floor. The floor fractured body induced by the lower stratified mining is basically within the failure range of the upper layer coal seam mining floor, and the mining failure zone and the water-bearing guide zone are not connected