Abstract: In order to investigate the effect of soil-structure interaction(SSI)on the earthquake characteristics,and the foundation pier effect of the soil surrounding on peak response of the continuous girder seismically isolated bridge with lead rubber bearings(LRB)under bi-directional earthquake excitation.An analytical method of earthquake-response is carried out in time domain using complex modal analysi,and the peak responses of a three-span continuous girder seismically isolated bridge are compared with consideration or ignorance of SSI effect.A parametric study is also conducted to investigate the effect of bearing parameters on the response of isolated bridge system.It has important effects of SSI on the earthquake response of continuous girder seismically isolated bridges.