In　order　to　resolve　the　durability　problem　of　expansion　joints　and　bearings,　the　integral　abutment　bridge　(IAB)　has　become　more　and　more　popular.　For　integral　abutment　bridge,　choosing　a　suitable　pile　foundation　type　is　a　challenging　problem,　because　the　substructure　is　fixed　with　superstructure　to　bear　the　load　together.　In　this　paper,　the　design　of　the　pile　foundation　in　a　fully　integral　abutment　bridge　(FIAB)　in　China　was　analyzed.　A　finite　element　model　was　built　by　the　commercial　software　MIDAS　considering　soil-structure　interaction　and　construction　stage　simulation.　A　sensitive　analysis　was　carried　out　to　investigate　the　influence　of　different　pile　foundation　types　on　the　mechanic　performance　of　the　IAB.　The　results　show　that　when　the　circular　pile　is　used,　the　stress　of　pile,　negative　moment　and　tensile　stress　of　girder　are　smaller　than　those　when　the　rectangular　pile　is　used.　With　the　increase　of　pile　diameter,　the　stress　and　displacement　of　pile　decrease,　while　the　bending　moment　of　pile　and　the　negative　moment　and　tensile　stress　of　girder　increase.　For　rectangular　piles,　with　the　increase　of　cross-sectional　length-width　ratio,　the　bending　moment　of　pile,　negative　moment　and　tensile　stress　of　girder　decrease;　while　the　stress　and　displacement　of　pile　increase.