Abstract: The Yuanjiawan landslide is a bedded rock landslide triggered by cutting the high and steep slope in the process of building Lanzhou-Lintao Expressway in Gansu Province. Under the influence and control of the complexity of the natural environment and various human activities in the course of slope transformation, the landslide occurs during excavation and exertion of the expressway. As a result, the landslide is typically characterized by repeatedness, succession, similarity and gradual increase, and the destructive forms are unique and diverse because of a variety of the changes of the human activities. Based on the geological conditions, the project features and the sliding characteristics and histories, the causes of occurrence and instability process and the evolution mechanism of the landslide are systematically analyzed using qualitative analysis methods of engineering geology and physical model tests, combined with quantitative analysis method of FLAC3D numerical simulation.