Abstract: Geomechanical model test was a kind of scale rule research method to specific geotechnical engineering problems based on the similarity principle.The geomechanical model could reflect objective physical bodies.Under the condition of meeting similarity principle,the model test could truly reflect the mechanical deformation properties of geotechnical medium.In order to conduct model test,we must have appropriate model test apparatus.According to the features of geomechanical model test,a combined geomechanical model test system which could carry out synchronous non-uniform loading was developed.The system was composed of box-type rack installation,load-change plate,and hydraulic pressure control test-bed,and there were such remarkable advantages as variable size,large scale and stable loading.The test system was applied in 3D geomechanical model test for a large-scale bifurcation tunnel project and the variation of displacement field,stress field of surrounding rockmass and the reinforcement effect of rock bolts in tunnel were effectively revealed.