Soft clay in different regions shows different dynamic characteristics. In this research, a series of undrained triaxial tests were carried out on the soft marine clay in the Zhoushan area using the Wille dynamic triaxial apparatus. The influence of different dynamic loading frequencies and cyclic stress ratios (CSRs) on the dynamic stress- strain- pore pressure and softening index of the soft clay were studied. Results indicated that the area corresponding to the stress- strain hysteretic curve under low- frequency loading is larger than others, and the curve is inclined to the strain axis. As the number of cycles increases, the softening degree of the clay increases (the softening index decreases), and a large cumulative plastic strain and residual dynamic pore pressure are generated under high CSRs. Under low- frequency loading with many cycles and high- frequency loading, it is necessary to pay attention to the influences of CSRs, in addition to the changes in accumulated plastic strain and residual dynamic pore pressure of soil caused by different values of confining pressure and axial deviatoric stress. Reducing the CSR can reduce the influences of different frequency loadings on the dynamic characteristics of the soft clay foundation. In addition, the cumulative plastic strain and residual dynamic pore pressure measured in the experiment are fitted with related correction models to obtain consistent fitting results. The results help as a reference for the application of Zhoushan marine soft clay in actual projects.