Abstract: In the high-altitude regions of China, such as Qinghai, Tibet, and Xinjiang, there are numerous gneiss open-pit high slopes, which pose hidden risks to mine safety production. Several slope failure incidents in recent years have highlighted the urgent need to study the deformation and failure patterns and mechanisms of gneiss open-pit slopes in alpine regions. This paper focuses on the September 14, 2023, landslide at the Jinbao Mine in Xinjiang. First, through field investigations and deformation monitoring, the characteristics and patterns of its deformation and failure were analyzed. Then, based on the mechanical parameters of gneiss foliation and rock mass under different conditions, discrete element numerical simulations were conducted to study the mechanism of slope deformation and failure. The results show that the landslide was a bedding deformation failure caused by upper bedding slip and toe compression-shear buckling. Under natural conditions, the slope remains stable. However, under the influence of freeze-thaw cycles, rainfall, and blasting loads, the shear strength of the gneiss foliation and the shear and compressive strength of the rock mass continuously decrease. This leads to an increase in the downward sliding force along the foliation in the upper part of the slope and a greater load on the lower toe. As a result, the rock mass at the toe bends, gradually fractures, and develops shear failure surfaces. These surfaces connect with the failure surfaces along the foliation in the upper part, forming a continuous failure surface, ultimately causing overall instability of the slope. The failure process exhibits clear retrogressive dynamics, where the lower toe fails and shears out first, causing the upper slope to lose support and settle. The conclusions of this study provide certain guidance for stability evaluation and prevention design of gneiss open-pit slopes in alpine regions.