Abstract: Piles are usually used to improve expansive soil.The behavior of piles in expansive soil will be influenced by the inundation swelling deformation of expansive soil.Large scale model tests were carried out to study the influence of inundation swelling deformation on the bearing capacity of single pile in expansive soil.The heave and swelling shear force of single pile were studied during inundation.It was indicated that the shaft resistance and bearing capacity of single pile would decrease and the heave and swelling shear force in piles would increase due to the inundation swelling deformation of expansive soil.