Abstract: As open-pit mining in China gradually advances into deeper excavation stages, the presence of steep slope structure, rock mass weathering, and the development of structural planes increasingly highlight the risk of landslides, posing significant threats to mining safety. This study focuses on an iron mine in Shanxi Province, utilizing data from 64 geological boreholes and the generalized Hoek-Brown strength criterion to construct a heterogeneous rock mass quality model. Based on the slope strength reduction method, a three-dimensional slope stability analysis is conducted. Combined with field structural plane surveys by UVA and numerical simulation analysis, the slope fail modes are identified, and the spatial distribution of the slope safety factor is obtained. Optimization schemes for the overall slope angle and prevention are proposed. The results show that: ①the failure modes of the slope are mainly dominated by the locally planar type, wedge-shaped body and overall sliding-tensile cracking type fails controlled by the layered structure. ②The stability of the current slope on the south side is relatively the worst. It is urgently needed to cut the slope at an overall slope angle of 44°, and after treatment, it can meet the requirements of the safety reserve coefficient. ③The three-dimensional slope stability analysis based on the heterogeneous rock mass quality model can provide a basis for the risk zoning and pre-treatment of the final slope. The research results have strong reference value for the slope stability analysis of similar high-steep and deep-concave open-pit mines.