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.