To investigate the development of longitudinal seismic damage of an extradosed bridge, a typical three-pylon extradosed bridge with pylon-girder-pier fixed system was selected as the prototype bridge and a 1/20-scale full-bridge shaking table test model was designed and constructed based on it.The El Centro wave and a site artificial wave were used as earthquake inputs and longitudinal shaking table tests were conducted.The seismic damage situation of the test model in each test case was observed.The test results show that the seismic damage of the pylon-girder-pier fixed system extradosed bridge mainly appears at the top and bottom parts of the piers, while the pylons almost kept elastic.With the development of seismic damage, the structural natural vibration period and the corresponding damping ratio increase gradually.Finally, severe damage appears at the bottom part of piers due to the crush of the core concrete.