Abstract: A photovoltaic base was built in an open-pit coal mine backfill area. Its booster station was located at the edge of the backfill area. There was a small kiln-pillar goaf under the eastern boundary of the booster station. During the operation of the booster station for 3 years, the backfill area had gradually subsided and tilted tower structures. Comprehensive geophysical surveys (ground geological radar, single-point seismic, and transient electromagnetic methods), drilling and drilling television surveys were conducted on the area to find out the backfill area status and the extent of deep goafs. Designed the overall reinforcement of the foundation by combining shallow grouting in the backfill area and deep grouting in the goaf.According to previous engineering practice, laboratory experiments, and field tests, it determined the slurry ratio and grouting parameters. After construction was completed, the geophysical comparison method before and after the treatment, the drilling core and fluid leakage observation method, the wave velocity test method, and the observation of surface settlement and deformation were used to analyze the treatment effect, and the grouting effect in the backfill area and the goaf area was good through inspection, which eliminated the hidden dangers of further subsidence of the booster station foundation and the sudden collapse of the goaf area, it provided a reference for similar projects.