The direct shear tests of heterogeneous structural surface in rock mass taken from the engineering site for Ling’ao nuclear power project are investigated under different normal stresses and water condition. The curves of shear stress- displacement change of heterogeneous structural surface are obtained; and the shear strength property and deformability of heterogeneous structural surface are analyzed. Comparison with the computing results using JRC-JCS model and the testing results is presented. The research results show that the shear stress-shear deformation curves of heterogeneous structural surface present an elastoplastic residual deformation and the saturated specimens have a smaller elastic region and enter into peak region or plastic region earlier. The shear stiffness of saturated specimens is lower than one of natural specimens under the same normal stress

especially for a low normal force. Water makes obvious effects on the strength parameters of rockmass heterogeneous structural surface; especially on inner friction angle . The JRC-JCS model can provide reliable values for the shear strength parameters of joints in a real geotechnical project.