In order to improve the commonality of research findings in the mechanical joint properties, the equivalent material properties of the mechanical joints were proposed. Based on GW contact model and Hertz-Mindilin contact theory, the Young’s modulus and the Poisson’s ratio of the equivalent material properties were deduced by the stiffness per unit area in the joint, which was obtained by the experiment. A bolted structure was taken as the example. The deformation of the structure was measured and analyzed under the different loads, which including the deformation of the structure’s joints. The comparison between the results of calculation and experiment validated the feasibility and effectiveness of the equivalent materical properties of the mechanical joints.