Abstract: This paper presents the triaxial consolidated undrained tests under K0 consolidation (CK0U) and isotropic consolidation (CIU) of a typical soft soil in Shanghai. The tests were performed by using the automatic triaxial apparatus. The variation of K0 under different confining pressures are analyzed. And the mechanical characteristics of soil samples under different confining pressures are studied. The results show that the K0 value has a decreasing tendency with the increasing confining pressures, the remolded specimens have a larger K0 than the natural undisturbed specimens of the soft clay. The main stress difference increases with increasing confining pressures. Compared with CIU test, the peak of the main stress difference by the CK0U test is larger. The strain at the peak point is smaller with the increase of confining pressures. The cohesive force value of the CK0U test is smaller and the friction angle value is larger. With the decrease of increment of each stage load, the K0 value is larger at the same condition of the maximum confining pressures of the soft clay, mechanical strength is higher.