Abstract: Research on the dynamic stability and sliding process of soil slopes based on particle flow theory is a new hot spot in landslide research in recent years. On the basis of field investigation and indoor experiment, the PFC2D program was used to simulate the instability failure movement process of the Xiamadazi landslide in Baowan village, Xingping township, Xiji county through the process of calibrating soil parameters, model establishment, power input, dynamic monitoring, etc., and the failure movement mechanism of the landslide is obtained. The following conclusions are obtained: ① The instability mechanism of the Xiamadazi landslide is that under the action of the earthquake, the leading edge of the slope is pulled and the trailing edge is pushed, causing the shoulder to be pulled and damaged. The larger velocity and displacement at the shoulder position after the instability is the main reason for the strong destructive force and the large disaster range of the earthquake landslide; ② The back wall of the earthquake-induced loess landslides is relatively flat, which is one of the important characteristics different from gravity landslides; ③ The relative altitude difference and length before and after the landslide obtained by particle flow simulation is more consistent with the actual situation. Therefore, the particle flow method can be used to predict the slip distance of earthquake landslides.