Abstract: The Flac^3D software, frequently-used finite difference software was used for slope stability transfusion numerical modeling. This modeling operation was based on the practice of In-situ leaching mining in an ionic rare-earth mine. Lots of parameters were obtained after large injecting of leaching solution, such as hole temperature-pressure, displacement field, safety factor and so on. The results show that hole temperature-pressure increases with the speed over 15 Kpa after injected leaching solution 5-20 days, and reaches 93.82 kPa in the final day; the displacement is expanded to -24.44 mm in a fast speed. The safety factor quickly reduces to 1.31 from 1.74 before construction. After the excavation of intercepting drainage, hole temperature-pressure remains at 85.33~85.61 Kpa if leaching solution injection lasting for another 10 days with accumulated maximum displacement being -25.26~-26.16 mm. The safety coefficient of slope achieves a stable level of 1.27 and the slope can maintain long-term stability generally.