Based on the deep foundation pit project of Hongqiao Station of Nanjing Metro, combined with the monitoring and measurement data of the foundation pit in the process of soil excavation, FLAC 3D software was used to establish a three-dimensional numerical simulation model of the deep foundation pit of the station so as to simulate the excavation and support dynamic construction process of the foundation pit. In addition, the deformation calculation results and monitoring data of the numerical simulation were compared. The research results show that:(1) the horizontal displacement of the diaphragm wall is in the range of the wall body, approximately in the shape of parabola. With the excavation of the foundation pit, it increases nonlinearly, and the peak value of displacement appears near the excavation working face of the foundation pit. (2) The influence of the surface soil by the excavation of the foundation pit is mainly in the range of 1H (H is the depth of the foundation pit), and the settlement curve under different working conditions is approximately parabola, and the peak value of settlement is linear Increase; under the same working condition, the displacement value of monitoring points at different positions presents a process of continuous redistribution over time, but the overall curve is still "concave". (3) The amount of foundation pit uplift is also related to the excavation process of foundation pit, the maximum uplift of soil occurs near the central axis of foundation pit, and the amount of uplift increases nonlinearly with the increase of excavation depth. (4) The erection of support can play a positive role in the deformation of the retaining structure and the settlement control of the soil mass, and the delayed erection of the support is extremely unfavorable to the development of the deformation.