Abstract: A non-linear time-history analysis of a high-level isolation structure under multi-dimensional seism is done by using the SAP2000 structural analysis software. The results of calculation and comparison show that the good effects are received in high-level base-isolation structure，especially the absolute acceleration response is greatly reduced; under multi-dimensional seismic，the responses of the structure with full symmetry and the same stiffness in each layer，may not be increased; but for the structure with podium and different stiffness of each layer，the responses will be increased. The podium can make a positive affect to shock isolation system of high-level structure.