Abstract: This study addresses the ongoing northward compression of the Indian Plate, which drives the rapid uplift of the Qinghai-Tibet Plateau, while subsequent river erosion has carved steep bedrock slopes across the surrounding mountain ranges. Slopes in the suture zone are notably higher than those recorded in earlier studies of the southwestern mountains. Their deformation patterns cannot be explained by a single model; these slopes fail in complex ways with poorly understood triggers, making it challenging to predict their stability accurately. This study focused on a steep inclined layered slope located at the Yarlung Zangbo River suture zone in the southeastern Qinghai-Tibet Plateau. Through an in-depth investigation of the regional geological setting, the slope deformation mass was categorized into three distinct zones based on elevation-dependent deformation features: (Ⅰ) toppling-creep deformation zone; (Ⅱ) superficial slip-deep tensile fracture zone; (Ⅲ) deep fracture-toppling-creep deformation zone. By integrating geological genesis analysis, the evolutionary process of slope deformation was elucidated. Key findings include two composite deformation-failure modes: (1) toppling-bending and creep-cracking; (2) sliding-collapse combined with buckling and creep-cracking. While large-scale ultra-deep instability is unlikely, progressive fracturing in zones of intense toppling deformation may lead to medium-to-large landslides, with potential slip surfaces ranging from 80 to 150 m in depth. The results provide theoretical insights for the stability assessment of similar high-altitude slopes with complex structural configurations.