<p>This study aims to evaluate the stability of a high-steep fractured rock slope on the right bank of Dongcuo River, Southeast Tibetan Plateau by establishing a multi-scale structural geological model. Multi-scale discontinuity information was first identified via unmanned aerial vehicle photogrammetry. The multi-scale structural geological model for the cross section of the slope was established by multi-scale discontinuity processing. In particular, large-scale discontinuities were directly embedded into the model, medium-scale discontinuities were realized via discrete fracture network simulation technology, and small-scale discontinuities were implicitly considered in the equivalent rock parameter calculation. A staged scheme for searching the shortest paths of the multi-scale structural geological model via Dijkstra’s algorithm was established. The searched shortest path with the largest discontinuity persistence passes the most fractures and processes the lowest shear strength, which can represent the critical slip surface (CSS). Three potential CSSs were selected for the quantification of the factor of safety (FOS) using the transfer coefficient method. Modified Jennings’ criteria were proposed to estimate the equivalent shear strength of the CSS composed of rock bridges and discontinuities. Finally, FOS is calculated as 3.81, implying that the studied rock slope remains stable.</p>