Abstract: This study addressed the limitations of conventional numerical simulation techniques for discrete rock masses and joints by introducing a novel method for assessing slope stability in open-pit mines. The approach integrates discrete element numerical analysis with UAV and 3D geological modeling technologies. UAV geodetic technology was employed to obtain DEM and DOM datasets. These datasets facilitate the development of a generalized model of the mining area using advanced 3D geological modeling techniques. Using a Discrete Fracture Network (DFN) system, the three-dimensional modeling of slopes with fully characterized structural surfaces was constructed. The slope stability was then quantified using FLAC3D and 3DEC software applications. The results show that the modeling technique for intricate terrains in authentic 3D numerical simulations, along with the three-dimensional modeling approach for jointed slopes using the DFN system, correspond more closely with practical engineering scenarios. The integration of UAVs and 3D geological modeling technology provides an effective method for ascertaining the stability of extensive open-pit mining regions. A case study of an open-pit mine in Inner Mongolia demonstrates the effectiveness of the proposed method. Post-excavation analysis indicates a vertical rebound of 5–7 cm and a maximum horizontal slope displacement of less than 3 cm, confirming the mine slope's stability. The computed stability coefficient, incorporating joint presence through discrete element numerical analysis, stood at 1.504. This value is markedly less than the 2.758 stability coefficient derived from traditional numerical simulations, thereby aligning the computational outcomes more closely with observed realities.