Abstract: To contribute to a better fundamental understanding of the deformation behavior for Suzhou quaternary sedimentary soils, using GCTS cylinder apparatus cyclic loading testing system, a total of 40 cyclic triaxial tests are performed on various kinds of undisturbed soils at depth less than 100 m corresponding to a wide strain range in the order of 10^-5 to 10^-2. It is revealed that the variation characteristics of the normalized dynamic shear modulus (G/G_max) and damping ratio (λ) with the increasing shear strain (γ) are strongly influenced by the sedimentary facies, depths and types of soils. The reduction of G/G_max with the increasing values of γ when γ <10^-4 is small, and the soils show nonlinear elasticity. Under the identical conditions, the test results demonstrate that the increasing depth shifts the values of G/G_max and the relationship between λ and γ. Moreover, the sediments of flooded plain facies are more linear and have slightly smaller values of λ with the increasing values of γ than the sediments of littoral facies. Under the same sedimentary facies and similar depth, the reduction rates of G/G_max with the increasing values of γ for silty sand, silty clay and clay have a descending order, and the values of λ under the same γ for silty sand, silty clay and clay increase successively.