Based on the measured data of a deep foundation pit of Nanchang Metro Line 4, FLAC3 D software is used to simulate the whole process of deep foundation pit excavation. The displacement variation law of adjacent pipelines caused by foundation pit excavation is analyzed from different pipe materials, pipe diameters, buried depths, buried distances and with or without internal supports. The results show that the internal support plays a good role in limiting the displacement of the adjacent pipeline during the construction of the foundation pit. The influence of pipeline factors is mainly concentrated in the first 6m of the excavation depth of the foundation pit, and the deformation of the pipeline gradually tends to be stable after 6m; the stiffness of pipe material has obvious influence on the displacement of pipeline in the process of foundation pit excavation. The larger the stiffness is, the smaller the settlement displacement of pipeline is. The influence of changing pipe diameter on pipeline settlement displacement is more significant than that of horizontal displacement, and the influence of pipe diameter on pipeline settlement displacement is greater than that of pipe material on pipeline settlement displacement. When the buried depth of the pipeline is 10 m, the settlement displacement is zero and the horizontal displacement of the pipeline is the largest. It is speculated that the underground continuous wall at the buried depth of 10 m is at the highest point of deformation, and relevant monitoring and protection need to be strengthened. The pipeline still has a horizontal displacement of nearly 1mm at a distance of 20 m from the foundation pit. It is concluded that the influence range of foundation pit excavation on the horizontal displacement of adjacent pipelines is greater than that of its settlement displacement.