Abstract: To further understand the mechanical properties of anisotropic structural surfaces, the specimens with gypsum-mortar structural surfaces in four joint roughness coefficients were made based on the standard Barton’s section lines of structural surfaces. Particularly, gypsum and mortar had the similar uniaxial compressive strength. Two kinds of curves between shear stress and displacement were obtained by indoor direct shear tests under three kinds of normal stress. Consequently, the change laws for peak shear strength of specimens with gypsum-mortar structural surfaces with the increase of joint roughness coefficients and normal stress were analyzed. Based on the numerical simulating results, the shear failure modes of anisotropic structural surfaces with similar strength were summarized. The curves between shear stress and displacement of anisotropic structural surfacess with lower roughness coefficients developed to the residual deformation stage after reaching peak values, while the curves of specimens with higher roughness coefficients evolved to the obvious softening stage. The growth rates of shear stress was positively correlated with roughness coefficients and normal stress. Under different normal stress, climbing failure, climbing-gnawing failure and gnawing failure occured successively to the anisotropic structural surfaces with similar strength as the roughness coefficient increased.