Dynamic shear modulus and damping ratio are two important parameters for seismic safety assessment of engineering site and earthquake response analysis of foundation. In order to evaluate the dynamics of seabed sediment of the selected area, the 10.3-84.2 m depth range of mucky silty clay, silt and fine sand are analyzed by using resonant column tests. The double logarithmic model has been built for the increasing trend of maximum shear modulus with overburden pressure. The research suggests that the existing standard values of shear modulus ratio and damping ratio are not suitable for seabed sediment, even the previous research results are just applied to a certain degree of strain range and natural stress state. Martin-Davidenkov model and the empirical relationship between damping ratio and shear strain has been used to build the variation law of shear modulus ratio and damping ratio with shear strain; and the dynamic shear modulus ratio and damping ratio of 5×10-6-10-3 strain range are used as recommended values. The study results may provide technical reference for marine engineering design, construction and seismic analysis.