Two boundary conditions are mainly considered in the geomechanical model tests, i.e., constant displacement boundary condition and constant stress boundary condition. Due to the characteristics of energy storage in deep rock mass media, the model boundary should be set at elastic regions to satisfy the uniformity stress on every point of boundary surface when conducting geomechanics model test. In addition, more attention should be paid to the overall stiffness of the testing apparatus at loading boundary, which can promptly supply the model a spring-back energy induced by excavation. Thus stress on the boundary can be adjusted automatically with the stiffness. The influence of apparatus stiffness on failure modes of surrounding rock is also discussed. The rebound stiffness of surrounding rock is calculated in the process of unloading by the elastic model and elastoplastic model respectively. The disc spring system is introduced to the loading apparatus and further designed based on the above calculated stiffness,,which is verified through the experiment as well. It has been believed that the new type loading and unloading test system can accurately simulate the real stress state of deep rock mass, and thus can be widely applied to geomechanical model tests.