Abstract: A set of isotropic and anisotropic consolidated-undrained triaxial test on undisturbed soft soils are conducted. The characteristics of shear strength, pore pressure and effective stress path are discussed. The test results indicate that the higher content of silt, the greater the shear strength, and the more obvious the dilatancy. The form of the effective stress path of soft soils converts from the elliptical arc to the s-shape gradually with the increase of silt content.