Abstract: To reveal the deformation and failure mechanisms of steep bedding rock slopes in Xizang, the temporal and spatial patterns of slope deformation were analyzed through a combination of field slope investigations and InSAR analysis. The deformation and failure mechanisms, as well as the critical conditions for slope instability, were examined from both qualitative and mechanical perspectives. The research results indicate significant phenomena such as rock bulging, flaking, missing rock layers, and crack development in areas with high vertical excavation heights and poor lithology, suggesting that rock collapse and instability have occurred in the past. Under the influence of vegetation growth, fallen branches and leaves, unloading rebound, snow cover, and frost heave, a maximum positive deformation zone ranging from 30 mm to 40 mm appeared in the natural slope area at the top of the slope. Conversely, due to unloading, rainfall, temperature fluctuations, and rock flaking, a minimum negative deformation zone ranging from -30 mm to -20 mm was observed on the slope surface in the excavation area. The deformation duration curves of monitoring points were classified into three categories: upward, stable, and downward. The upward and downward curves were further subdivided into three and four subcategories, respectively. The slope underwent several stages before and after excavation: unloading rebound, rock plastic deformation, and rock compression sliding. The missing rock layer was attributed to shear sliding of the upper rock layer caused by compression failure at the base of the slope due to creep. Some monitoring points on the slope surface in the excavation area exhibited signs of unstable creep. To prevent damage to the main rock layers of the slope under extreme rainfall or strong seismic events, it is recommended to use anchor rods, anchor cables, or slope cutting to reinforce the dangerous rock layers. A theoretical analytical formula for the compressive stress of the main control rock layer and the critical self-stabilizing height was derived. The critical self-stabilizing height is directly proportional to the uniaxial compressive strength and shear strength parameters of the adjacent main control rock layers, but inversely proportional to seismic acceleration, slope inclination, density, and thickness of the main control rock layer. The findings of this study provide valuable insights for understanding the mechanisms and stability analysis of disasters caused by steep and inclined rock slopes.