The study of the complex relationship between heat losses and variable stiffness under different material ratios has important significance to improve the vibration isolation performance of a laminated Magnetorheological rubber bearing(MRB). Based on magnetomechanical coupling theory, the macroscopic and microscopic magnetomechanical coupling models are constructed for the bearing. In further, the magnetic field distribution and stiffness of horizontal shear of the bearing are calculated. Considering the influence of heat losses, the relationship between the range of stiffness and the particle volume ratio of the magnetorheological rubber(MRR) is obtained. The bearing is sheared on the MTS tester, and the experimental data are compared with the theoretical results. Results show that the designed bearing can obtain the maximum range of stiffness up to 428% while the maximum heat loss is limited within 387 W, and the optimal particle volume ratio of the MRR is 12%. Besides, the optimal particle volume ratio of the MRR deviates with the changes of heat losses. Therefore, the balance law of heat losses and variable stiffness obtained by this macroscopic and microscopic theory model can provide a novel way to design the optimal structure and properties of MRB.