A series of artifical calcareous sand - steel interface direct shear tests was performed. It shows that the contact relation ship of the interfaces is frictional; and the curves of shear - normal stresses ratio vs shear deformation under different normal stresses are almost identical. Negative dilatancy of the sand under constant normal stresses is quite large. Shear strength under constant volumetric shear test is far below that under constant normal stress condition. Load and unload curves are almost superposition. There is a trend of shear strength debasement after cyclic shearing. And the wet friction coefficient of the interface is less than the dried one.