Abstract: The shear modulus and damping ratio of EPS composite soil, as a kind of artificial filling material, are the key parameters to analyze the dynamic stability of embankment. 15 cyclic torsional tests are conducted on the hollow cylindrical samples of EPS composite soil to study its dynamic characteristics. The characteristics of skeleton curve, dynamic shear modulus and damping ratio for EPS composite soil are analyzed. The influences of mixing ratio and initial consolidation state are discussed. It is found that the EPS composite soil is characterized by typical dynamic non-linearity which is controlled by the strength of cemented soil and the initial stress state, but EPS bead content has no obvious influence on the initial shear modulus. After EPS composite soil enteres the non-linear deformation stage, EPS beads have a remarkable weakening effect on its strength. The “structural damping” effect induced by the dynamic behavior of the weak interface formed between EPS beads and cemented soil is an important component of the damping mechanism for EPS composite soil. The initial shear modulus increases with the increase of the initial minor principal stress. And the modulus attenuation characteristics are significantly influenced by the initial minor principal stress and EPS bead content. Based on the test results, the empirical models are given to describe the skeleton curve, modulus attenuation and damping growth characteristics for EPS composite soil.