Abstract: A new solution technique for the dynamic response of the structure with elastoplastic hysteretic base isolation devices has been developed. The proposed approach can offer an exact solution for dynamic response of base-isolated structure by means of the mode superposition method in each elastic and plastic phase, between which the transitional time must be obtained and employed. The proposed method combines merits of both analytic and numerical method. Therefore, it not only requires much less computational effort, but also thoroughly avoids the trouble such as accuracy, convergence and stability encountered in many other numerical procedures.