Abstract: The underlying soils have various degrees of consolidation in engineering. And the dynamic stiffness will change in different patterns, which will affect the dynamic strength of soils and thus cause uneven settlement. Dynamic triaxial tests on Hangzhou saturated soft clay are performed to study the effects of consolidation degree, consolidation stress, cyclic stress ratio on the change of dynamic stiffness. A new model for stiffness change considering the degree of initial consolidation, cyclic stress ratio and threshold cyclic stress ratio is proposed on the basis of the tests and the existing research findings. The results reveal that under the same consolidation degree the dynamic stiffness will increases with the increase of cyclic numbers due to compaction of soil particles, as long as the cyclic stress is small enough. The soil stiffness will change from hardening to softening with the gradual increase of the cyclic stress ratio. The higher the dynamic stress ratio, the greater the degradation of stiffness. Under the same cyclic stress ratio, the dynamic stiffness will be gradually intensified with the decrease of the consolidation degree. There is a nonlinear relationship between the dynamic stiffness and lgNof the saturated soft clay.