Abstract: Real time leakage detection and disposal is an important means to improve power supply reliability and avoid personal electric shock. In response to the shortcomings of current leakage detection methods and devices, this article develops an online leakage detection device for low-voltage distribution outgoing lines, which can monitor the leakage situation of low-voltage outgoing lines in real time and quickly locate the leakage position. The device is easy to operate, does not require professional maintenance, and has low operating costs. It can improve the reliability of low-voltage power supply and avoid economic losses and personal injuries caused by leakage.