High damping rubber bearing（ HDRB） as a kind of isolation bearing has the functions like bearing capacity,restoring force and damping（ energy absorption）. In this paper,a regular continuous girder bridge isolated with high damping rubber bearings was taken as a research object. A simplified Two Degrees of Freedom mechanical model was established in Opensees software,and compared with the FEM model established in SAP2000 to study the feasibility and accuracy of the simplified mechanical model. The results show that the response amplitude of the isolation bridge can be accurately calculated by the simplified mechanical model. Under the same seismic waves,the analysis results obtained from the simplified mechanical model meet the engineering accuracy and agree with the FEM model.