Abstract: Despite of its advantages, in-situ leaching mining method has an obvious disadvantage, that is, landslide caused by injected leaching solution. Numerical simulation is performed on the slope stability by using FLAC3D and strength subtraction. The stope slope instability region is regarded as key monitoring area. The field observation shows the instability of the mountain part is in conformity with the simulation results. Combing with field monitoring data in the 7 consecutive days, the grey prediction model is established based on grey theory, predicting precision grade being favorable. It can be applied to the engineering practice, which provides reference for the subsequent landslides warning.