Abstract: With the rapid development of engineering construction, more and more deep foundation pits have occurred, while there are usually intensive engineering piles in the bottom of deep excavation. At present, the researches on engineering piles in the bottom of excavation are not comprehensive at home and abroad, and construction accidents are often caused because of unreasonable excavation or wasting resources due to blind piling with little understanding of this in actual engineering. For two cases of no piles and pile groups in the bottom of excavation, the changes of ground displacement, soil uplift on the bottom of excavation, structural deformation, structural moment and lateral earth pressure are compared by means of the finite element software ABAQUS. The deformation behaviors of the foundation pit and the stress characteristics of retaining structures are investigated under deep excavation unloading conditions. Finally, the changes of pile-soil relative slip, pile shaft axial force and skin friction under various excavation steps are analyzed, and the stress characteristics of the piled foundation under excavation unloading conditions are gained.