This paper adopts the tilt photography technology, builds the drone auxiliary tool, completes the camera calibration, aerial survey planning, image overlap and regional boundary coverage, and other processing work in turn, and then obtains the real scene data of the valve hall of the DC converter station. After processing and reconstructing the acquired image with texture mapping technology, the valve hall of the DC converter station is modeled by integrating BIM and 3D reality modeling technology. The finite element method is used to model and analyze the surface electric field of the valve hall model for electromagnetic changes. With different spatial locations, the electric field strength of the valve hall is different. When the frequency is 125MHz, the electric field strength value is the largest, 130V/m, and then the electric field strength decreases rapidly, and the average value of the electric field will no longer be more than 120V/m after 150MHz.Comparison and analysis of the electric field strength spectra of the different measurement points with the background noise outside the valve hall, and the spatial electromagnetic field of the valve hall of the DC converter station in normal operation are analyzed. The frequency range of measurement points 1 and 2 is below 8×108 Hz, and the maximum electric field intensity around 2×108 Hz can reach 180dBµv/m.