Based on the problem of adjacent construction of overpass bridge foundation and deep foundation pit of the underground station, this paper carried out a finite element numerical simulation of the whole construction process with Midas GTS NX where modified Mohr-Coulomb constitutive model was adapted on the soil, including foundation pit excavation, bridge foundation construction and braces demolition, to study the pattern of interaction between the bridge foundation and the underground station foundation pit. Having compared the numerical simulation results with on-site measured data, the results proved the accuracy of the simulation and showed that, during the excavation stage of the foundation pit, the deformation of the foundation pit continued to increase due to the horizontal unloading of the soil. The maximum settlement occurred at about 0.4 times the width of the foundation pit from the edge of it, and the maximum displacement of diaphragm wall occurred near the bottom of foundation pit. After the construction of the overpass bridge foundation, the surface settlement of the foundation pit and the lateral displacement of the diaphragm wall further increased, and the overpass bridge itself also had a modicum settlement. Thanks to the protection of the enclosure structure, the impact of the braces demolition was neither obvious on the pit nor the overpass bridge foundation.