In this study, an efficient damping system for continuous girder bridges (EDBs) is proposed to improve the energy dissipation efficiency by amplifying the relative displacement of the dampers. To investigate the applicability of this damping system in the seismic resistance of continuous girder bridges, an experimental model of both common and magnified viscous dampers with triple displacements is designed to conduct a reciprocating loading test under the action of a sine wave. The amplification effect is verified by comparing the test results with those under ordinary dampers. Finite element software is used to establish a multi-mass point model of a six-span continuous bridge to analyze the pier bottom shear force, pier bottom bending moment, displacement, hysteresis curve, and energy dissipation curve of different damping schemes under the action of three seismic waves. The results show that the efficient damping system of the continuous girder bridge effectively dissipates the seismic energy and reduces the seismic response of the bridge structure.