Abstract: Excavation of large foundation pits often has unfavorable effects on the surrounding environment. Taking a mega-shaped deep foundation pit in Nanjing as an example,combined with finite element software for modeling analysis,the effects of different excavation and construction stages on the deformation of the supporting wall and the deformation of the space around the pit were analyzed. The calculation results show that the displacement of the soil outside the pit is closely related to the deformation of the retaining wall. The ground settlement in the long direction is about twice that in the short. The ground settlement at the middle is greater than the ground settlement at the corner which is about four times that the corner. It shows that the excavation of the foundation pit has greater impacts on the central part and less on the corner,and there is a significant spatial effect on the surrounding environment.