Considering the characters of soils,such as expanding when unloading and hardening when loading,constitutive model Hardening-Soil which is more applicable to soil body was adopted to simulate the deformation of supporting structure of a deep foundation pit at excavation stage.By calculating the axial force change of internal bracings,the torque change of retaining piles and the horizontal displacement of piles at different stages of excavation were presented out.The calculated results reflected the characters of soil body well,provided a reference for the engineering design and construction.