In order to study the spatial effect characteristics of surface settlement at different characteristic locations during subway pit construction under the action of non-equilibrium loading, a subway station pit project in Nanchang is taken as the background of the study, and a three-dimensional numerical model is established by using PLAXIS 3D software for simulation and analysis. The simulated values are in good agreement with the measured values, which verifies the accuracy of numerical simulation. By changing the size of the non-equilibrium loading outside the pit, numerical studies were carried out under two working conditions, on the basis of which the surface settlement response at different characteristic locations outside the pit under different conditions was studied. The spatial effects of surface settlement outside the pit under different non-equilibrium loading and dewatering schemes were discussed.The results show that non-equilibrium loading has a greater impact on the surface settlement on the long side of the foundation pit near the loading side, and the surface settlement on the near loading side is generally greater than the far loading side. Under the condition of step-by-step dewatering excavation, the surface settlement at different characteristic sections outside the pit is relatively small. Step-by-step dewatering excavation of the foundation pit has a certain inhibitory effect on the surface settlement outside the pit. under the action of non-equilibrium loading, the surface settlement distribution outside the foundation pit has a significant spatial effect. At the same time, the spatial effect of surface settlement in each study area of ??the one-time dewatering excavation was greater than that of the step-by-step dewatering excavation condition.