Abstract: Based on a large amount of on-site blasting vibration monitoring and signal analysis, the approximate viscous damping ratio of the earth dam was obtained, and the quasi-two-dimensional model of an earth dam was established based on the dynamic response characteristics of the dam by FLAC^3D. The Rayleigh wave distribution of the dam foundation was obtained based on the calculation and simplification of soil mechanical parameters, and the main frequency of the dam body was determined. The frequency of the most unfavorable seismic waves was 2.00 Hz. The velocity threshold of dam damage was 16 cm/s by increasing the amplitude of the worst seismic waves, and the threshold was taken as the safe vibration velocity of the dam, which effectively guaranteed the safety of the dam. In this paper, dam vibration speed was predicted by FLAC^3D, which can be referred to and used by production and scientific research units.