[Objective] To study the effect of three-dimensional topography on shear strength and reveal the shear essence of structural plane, in order to provide the basis for understanding the properties of structural plane. [Methods] A 3D laser scanner and a 3D printer was used to completely recast the artificially fabricated structural interview samples. The direct shear test was conducted indoors under the normal stress level 5, to record the surface topography change before and after shearing. The FLAC 3D numerical simulation software was used to simulate the shear mechanical movement of the structural plane under different normal pressures. The distribution of shear stress on the surface of structural plane was analyzed and summarized. [Results] The peak shear strength of the structural plane was related to the normal pressure and three-dimensional topography of the structural plane. Under the same shearing force, with the larger normal stress, the shearing contact area, the shearing stress and the scope of the shearing stress were larger. The small bulge at the top of the structural plane surface was significantly sheared, but the damage area of the small bulge at the lower part was not obvious, indicating that the bulge at the higher part of the structural plane was easier to be sheared. [Conclusion] With the increase of normal pressure, the magnitude and range of shear stress increase, but the region does not change obviously.