Abstract: According to coal mining conditions of Huainan Xinji mining in No.3 mining district, the movement and deformation characteristics of surface were simulated and analyzed by FLAC with coal mining of thick soil layers. The influences of different mining scheme on dyke of flood were analysed on the conditions of geology and mining. And the dyke movement and deformation characteristics of different distance between working face without coal pillar and dyke were further studied.The results provide some scientific references for safely mining and reinforcing the dyke.