Abstract: Landslides often occur in the Bailongjiang River basin, and the disaster mechanism is complex, taking Jiangdingya landslide in Zhouqu County as the background, the deformation and failure mechanism of the accumulation landslides is explored, and the stability calculation model is improved by means of physical model tests, theoretical analysis and finite element numerical simulation. The results show that: (1) The scour of the river water has a tractive effect on the landslide, which is an unfavorable factor. (2) The superposition of adverse factors of rainfall after earthquake belongs to the disaster chain effect. After the earthquake, the strength of the landslide soil decreases, and then the rainfall infiltrates in the landslide soil along the sliding direction, and the rise of the river water caused by the rainfall will enhance the scour effect of the river water in the front of the landslide. (3) Under the coupling action of earthquake and rainfall, the cracks in the middle and rear of the landslide model develop obviously, and the deformation of the front edge of the slope is large. The deformation characteristics are consistent with the actual situation. (4) Based on the unbalanced thrust method of the broken line sliding surface landslide, the formula for calculating the stability of the accumulation landslides under the coupling action of earthquake and rainfall is improved by comprehensively considering the effects of inertial force of earthquake and seepage force. The calculated stability coefficient of the landslide under the coupling action is calculated to be low, which is unstable. The research results may provide a scientific basis for the stability analysis and prevention of similar landslides.