Abstract: Dynamic model parameters of earth and rock material are the main factors affecting anti-seismic safety analysis of earth-rock dams. Differences between the parameters determined by laboratory test and the actual parameters are more or less inevitable due to the influence of construction techniques, methods and quality. To solve the problem, we put forward a dynamic model parameter inversion method that takes the acceleration response spectrum as object function, in which the dynamic parameters of embankment material are inverted by particle swarm algorithm according to the response information of dams in earthquake. The results show that the attenuation curve of dynamic shear module and the cumulative curve of damping ratio have significant influence on seismic response of dam.