Abstract: In view of the current single-phase grounding fault of medium and low voltage lines, it is unable to provide fast, accurate and effective troubleshooting technical means, resulting in misjudgment of fault points, affecting line maintenance and power supply recovery, resulting in increased maintenance costs. Based on the technology of BeiDou (GNSS) system and the positioning principle of phase method, when a single grounding fault occurred in medium and low voltage overhead, cable and hybrid lines, the AC signal was injected into the line fault phase under off-line state, and the AC signal detector was used to detect along the line trend. When the hand-held detector detected the fault point and sends out an alarm and the waveform phase reversal, it could be judged as the line grounding fault point, which could realize the rapid positioning and search of line grounding fault, effectively help the continuous improvement of equipment fine operation and maintenance, emergency disposal and other capabilities, enable the establishment of digital teams, improve the work quality and efficiency of teams, and promote the innovation of grass-roots management mode.