G281 grid is the key infrastructure to ensure that the safety and stable operation of the power grid and the personal safety. Buried in the ground, restricted by the surface buildings, the grounding grid is difficult to detect and maintain. In order to overcome the difficulty of high-voltage transmission and detection in substation grounding grid, a detection system based on ground penetrating radar (GPR) was presented in this paper. This system can visualize the visual image of grounding grid, diagnose it on the ground surface without power cut and excavation.