Abstract: On the experiment of Wang Huan-ding, an elasto-plastic biaxial hysteretic model for variable stiffness base isolator made of concrete-filled steel tubular short column is proposed in this paper. The proposed model can be used for elasto-plastic analysis of structure easily. Continuous smooth functions are used in the hysteretic model. The frictional forces are modeled as a velocity-dependent damping force. The requisite parameters of the proposed model can be acquired directly from the test curves of the bearing.