Abstract: The comparative analysis on fundamen tal engineering pro perties of the soft soils in the underlying stratum of eastern breakwater and corresponding sea area inside the breakwater of north harbor is investigated for the Qiong Zhou Strait railway ferry project.The results show that the mois ture content, void ratio and coefficient of permeability for the soft soils in the underlying stratum of eastern breakwater decrease slightly after construction, h owever, its mechanic al index and microstructure do not deteriorate,and hav e the typical feature of structural soft soil compared to the corresponding soft soils in sea area. Therefore, the underlying soft soil still keep its structure intact relatively,and have not been damaged apparently under the loading of breakwater,and can be used as bearing stratum of breakwater.The resu lts of stability analysis and deformation monitoring as well as the existing sta te of breakwater verify the above conclusion.