In order to study the seismic response performance of coastal extra-large elevated bridge, the influence of substructure is analyzed and the bridge design is optimized, which provide reference for the seismic design of project. Taking an engineering project as an example, a three-dimensional dynamic model is established to analyze the influences of different pier sizes and pile foundation schemes on the seismic response of the bridge, and the ductility seismic design of the bridge is checked. The results show that with the increase of pier size and pile foundation number, its own bearing capacity will increase, but the synchronous seismic response will also increase. Therefore, it is necessary to select the economic and reasonable section size and pile foundation number. According to the analysis, two selected design parameters can well meet the requirements of ductility seismic design under the earthquake action.