Nowadays,　many　simply　supported　bridges　constructed　all　over　the　world　have　been　affected　by　the　durability　problems,　especially　broken　expansion　joints　and　damaged　bearings.　In　order　to　resolve　fundamentally　the　durability　problems　of　existing　bridges　during　their　service　life,　the　concept　of　integral　abutment　bridge　came　out.　In　this　paper,　the　retrofit　technology　with　the　concept　of　integral　abutment　bridge　was　analyzed,　based　on　a　simply　supported　bridge　＇Viadotto　Serrone＇　in　Italy.　The　corresponding　finite　element　models　of　the　existing　jointed　bridge　and　four　types　of　fully　integral　abutment　bridges　after　retrofit　were　built　by　Sap2000.　Using　the　finite　element　model,　the　sensitive　analysis　choosing　the　substructure　height　as　the　critical　influential　factor　was　carried　out.　Some　regulations　obtained　can　be　adopted　as　the　guideline　of　this　retrofit　technology.