To explore seismic damage history from sound to collapse of reinforced concrete continuous bridge based on shaking table test, the collapse analysis of two-span continuous girder bridge model is carried out, and then a single collapse criterion is established at a structural level. Based on the key components of collapse, the overall evaluation index of seismic damage of the two-span continuous beam bridge D is proposed, and the criteria for the classification and damage grades are presented. Numerical analysis results show that the energy ratio index proposed in this paper can effectively identify the time of earthquake damage and even the time of collapse. If the energy ratio is not more than the limit, the bridge will collapse. The middle pier and fixed bearing are the key components. It is proved that index D proposed on the key components can assess the damage of the two-span continuous girder bridge model with different degrees. This evaluation system can also provide a reference for seismic damage assessment and seismic retrofitting of the same kind of bridges.