Numerical simulations for the excavation of asymmetrical foundation pit is formed on both sides of soil mass near the subway station with the finite element software of MIDAS/GTS. In this paper, the deformation characteristics of the foundation pit of the semi-infinite soil body on one side and the semi-infinite soil body on the other side were analyzed in details. The comparative analysis was conducted with field monitoring data. It was found that under the typical stratum condition in Xiamen, the deformation of finite soil side of foundation pit was obviously less than the infinite soil side, and the influence range of the width of soil on finite soil side of the foundation pit was about 1.5 times of the excavation depth. Specifically, with the increase of the width of soil on the finite soil side of foundation pit, the heave values increased while the surface settlement and the horizontal displacement of pile on the infinite soil side of foundation pit decreased. The surface settlement and the horizontal displacement of pile on the finite soil side of foundation pit increased and the deformation of foundation pit gradually changed to the deformation when both sides of foundation pit were infinite soil sides.