Abstract: A new-style structural seismic isolation system is put forward by adding the isolation device in to a mega-frame-sub- truss-frame system. The system's seismic response under several earthquake waves, such as the dynamic time history response, isobtained by using a general finite element program ANSYS to calculate the seismic isolation and resistance performance. The calculation results show that the mega-frame-sub-truss-frame system is a well-behaved structural seismic system. It has good seismic resistance performance and improves the mega-frame's load -carrying properties: The culmination displacements are reduced observably relative to the original structural system without the isolation device. The specific data are that the culmination displacemen t are reduced approximately by 47% in main-frame and by 64% in sub-frame. The maximum seismic internal force response value i s also inferior to the original structural system. The shear force is reduced approximately by 33% and the bending moment is reduced by 34%. The calculation results have an important referential value to the seismic design of mega-frame structural system.