Abstract: Based on the geological environment of deformation and instability in south slope of Fushun West Open-pit Mine, we analyze the deformation characteristics, influencing factors and stability of defomation body. The results show that the deformation body is bedding rock slope landslide formed by mining, which is affected by slope structure, deep pit structure, rainfall, weak zone and the bottom excavation and belongs to extremely big and dangerous rock body. Through numerical calculation and comprehensive monitoring results, we think that the stability of asymptotically stable deformation body is decreased in the rainfall condition and has a higher possibility of disaster, which needs to carry out monitoring work. We present technical measures for slope stability control.