Abstract: The bearing capacity of piles is evidently affected by the shear fatigue effect on pile-soil interface. A serious of full-scale tests and constant normal stiffness shear tests are conducted to study the shear fatigue on the interface of soils and PHC pipe piles. The results show that the shear fatigue is closely related to shear cycle number, which can be expressed as a power function. The degradation coefficient is 0.45. The shear behavior can be simulated by the constant normal stiffness shear tests. The shear stress between concrete and clayey silt displays decay power type trend with the increasing shear cycle number, and most of the reduction occurs in the first few cycles and reaches a steady value after about 20 cycles. The degradation coefficient is 0.41, which is closed to the results obtained in field tests.