In order to study the seismic response performance of the viaduct in front of the airport station according to American code, the influence of the bridge substructure is analyzed to guide the design of the viaduct. Taking a viaduct of a Southeast Asia airport as the study object, the model is established by using the finite element software to analyze the influence of its unconventional pier-column size on the seismic response of the overall bridge structure, and to check the ductile seismic design of the bridge. The results show that the variable section cylindrical piers with large top and small bottom are adopted, and the main beam adopts an integral box girder with a width of 32.8 m. Through the check of control section, it is shown that the pier bottom is the weaker section. The content can provide reference for the seismic engineering of other similar bridges.