Abstract: The leakage of low-voltage lines and equipment not only causes direct economic losses to power supply enterprises, but also poses a threat to power grid operation and personal safety. By monitoring the change rule of the line loss rate in the low-voltage substation area, we can timely find and quickly treat the potential leakage hazards of different types of low-voltage power grid, and eliminate the potential safety risks. This method has achieved remarkable results in practice in recent years.