The problems of electromagnetic interference caused by lightning strikes are important research topics in the building lightning protection area. The spatial distribution of the magnetic field around elevated subway station is simulated using the finite element method (FEM) when struck by lightning. The method of magnetic field numerical simulation by use of FEM in the IES electromagnetic simulation software is introduced, and taking the Changyang elevated subway station in Fangshan as an example, the distribution of the magnetic field is obtained through the following process: model building, material setting, excitation source applying, mesh generation, postprocessing, etc. Then the spatial distribution of the magnetic field is presented in figures, and the features of the magnetic field are analyzed. The intensity and scope of lightning magnetic interference are determined, and the corresponding protection methods and measures are proposed. Finally, the attenuation of the magnetic field and the safe distance from the equipment to the downconductor are calculated after the shielding measures being taken in the elevated station.