To study the influence of underground mining on the deformation and failure of the overlying open-pit mine dump, the Suancigou coal mine and the Harwusu open-pit mine dump were taken as the research objects, and the regulations of surface subsidence and its induced dumps were analyzed. The mechanism of deformation and failure was predicted by the probability integral method, and the deformation and surface subsidence of the dump were analyzed with the FLAC3D software. At the same time, the displacement changes of the Harwusu open-pit mine dump after the stoping of Suancigou coal mine working surface were analyzed. The results shown that the maximum subsidence predicted by the probability integral method was about 21 m, and the maximum subsidence calculated by FLAC3D simulation was about 22 m. The maximum surface subsidence of both increased first and then gradually stabilized with the progress of the mining phase. The surface subsidence forms the regulation of moving basins. The numerical simulation results were consistent with the actual location of the subsidence area. The horizontal displacement of the dumping was positively correlated with the advance length of the working face. In the direction of the working face, the horizontal displacement on both sides of the goaf was the largest, showing the characteristics of sliding to the middle of the goaf, and the overall performance was that the horizontal displacement of the left slope is greater than that of the right slope.