Abstract: In view of smaller horizontal stiffness of laminated rubber bearings, a new mega-frame with isolated suspension structure was proposed, and the two-mass simplified model of which was presented for dynamic analysis. The seismic responses of two cases were investigated for traditional mega-frame and the proposed new mega-frame with isolated-suspension structure respectively. For analyses of the damping effect, the relative displacements of main structure in both cases were compared based on frequency domain transfer function. According to the results of frequency analysis, three-dimensional finite element models were established and analyzed in time domain by two typical seismic wave. Results of analysis from both domains indicate the mass ratio and frequency ratio of mega-frame to suspension structure are correlative on damping effects. The relative displacement of mega-frame is reduced by more than 40% if the sum of frequency ratio and 10% mass ratio is not larger than 0.7. The damping effect on the mega-frame is negatively influenced by pulse-like ground motions, but seismic action effect is not be amplified.