Abstract: This paper investigates the three-layer structural soft soil that widely exists in Fuzhou Basin. First, the sedimentary features and conventional physical mechanics properties of the three soils are illustrated respectively. Then by means of the resonant column test instrument, a series of dynamic tests are conducted with different consolidation stresses to attain the dynamic damping ratio λ of different structural soft soils under the effect of dynamic load. The relation curve of damping ratio λ and shear strain γ is presented by virtue of numerical analyses to further analyze the differences of test results for different structural soft soils. Tests show that the relation of dynamic damping ratio λ and shear strain γ doesn't have strong correlation with consolidation stresses and the curve λ-γ of three-layer structural soft soil has large difference when the range of shear strain is between 0.00001 and 0.01. The test result will provide reliable data for further understanding the seismic effect of soil layers in Fuzhou Basin, and it is of real significance.