Through the analysis of engineering geological factors of the resurrection of ancient landslides, it is found that the basic idea of evaluating the mechanism of the resurrection of ancient landslides. Taking the Luoyugou ancient landslide in Gansu province as an example, Using the methods of field geological investigation and numerical simulation, combined with the engineering geological conditions in the landslide area, the genetic mechanism of the Luoyugou ancient landslide was analyzed. The disaster model is as follows: Because of the excavation of the front edge of the slope, a high and steep free surface was formed, then the tensile stress concentration of the posterior edge of slope body , which aggravated the crack joint expansion and strongly reduced rain water infiltration, which lead to the instability of the ancient landslide triggered by the rapid increase in the gravity of the soil. At the same time, the dynamic characteristics of the ancient landslide were calculated by using the sleigh model, the results show that the maximum velocity of the sliding body reaches 11.56 m/s. The stability of ancient landslide was evaluated by using finite element software flac3d. The displacement diagram, stress-strain and other disaster characteristics of ancient landslide under two different conditions of gravity surface load and gravity surface load rainstorm are obtained. These provide a reference for the analysis of similar ancient landslides disaster prevention and mitigation in northwest China.