Because the localizer's effective coverage of the electromagnetic radiation field is directly proportional to its deployment altitude and terrain conditions. As a result, the LOC antenna model was designed, a high-performance GIS platform was built, and a digital elevation digital terrain model based on SRTM data was constructed, all in accordance with the terrain environment surrounding the localizer. The Deygout algorithm was used to estimate radio diffraction under terrain shielding when combined with the radio signal transmission model and attenuation model. The software design of the simulation and evaluation system for the coverage of the localizer radio under the terrain was realized, the software can simulate and analyze the effective coverage of the localizer radio.