Abstract: Combined with numerical simulation and statistical analysis, the deformation of diaphragm walls and surface settlement of deep foundation pit in Taiyuan area are analyzed. The factors and rules affecting the deformation are caculated by using finite element numerical simulation. The deformation control standard of deep foundation pit engineering in Taiyuan is determined combined with the measured results. The results are as follows. The maximum lateral displacement of the diaphragm wall and the maximum ground subsidence increase linearly with the increase of excavation depth, and decrease with the increase of insertion ratio. The ground subsidence is mainly distributed in the range of0≤d/H≤2. 5. It is suggested that the deformation index of foundation pit in Taiyuan can be selected according to δ_hm/H≤0. 15%,δ_vm/H≤0. 25%, and the ground subsidence in the range of 1. 0 Haround the foundation pit should be strictly controlled, which has certain guidance for the design and construction of deep foundation pit.