Abstract: Soil structure has significant influence on its engineering properties, the formation of soft soil structure in Ningbo area is analyzed from the internal cause and external cause. To analyze the soil structural effects, by means of onedimensional consolidation test and consolidated undrained triaxial test, differences of compression properties, properties of pore water pressure, and strength properties which are caused by structural property are systematic analyzed by contrast with the test data of undisturbed sample with remolded sample of typical mucky soft soil in Ningbo area. Finally problems which should be considered in constitutive model for Ningbo clay on the basis of experiment results are presented.