With the increase of the urban building density, the building groups in soft soil area are also increase, the foundation pit construction is restricted by the strict environments. Timely and effectively predicting the deformation caused by foundation pit construction and the impact on the surrounding environment, summarizing foundation pit deformation control technologies and the measures and verifying the implementation effects have important guiding significance for the design and construction of deep foundation pit in soft soil areas. Combined with the engineering practice of a foundation pit project in Nanjing, by means of theoretical analysis, numerical simulation and construction monitoring, the deformation caused by deep foundation pit excavation in soft soil area and the control methods are studied.