Abstract: Based on the basic principles of the finite difference method, the study was performed using FLAC3D software to analyze the dynamic response of the reservoir dam under seismic loadings. The earthquake intensity and the height of the reservoir's water level are studied as the key factors to the reservoir dam. The results show that as the earthquake intensity increases, the degree of liquefaction of the dam foundation increases, and the vertical sink of the dam crest increases; As the water height increases, the degree and scope of the liquefaction area of dam foundation increase, vertical sink and deformation of the dam crest increase. When the height of the water storage is 10 m and the peak acceleration of the earthquake is 0.4 g, the dam crest sink is about 0.13 m, the dam stability is decreased, and an obvious potential sliding surface appears. Therefore, in the site selection, design and construction of the reservoir dam, attention should be paid to the earthquake disaster of the liquefiable foundation and the corresponding anti-liquefaction and reinforcement measures should be taken.