The utility model relates to a cable power distribution network, and especially relates to a distribution network cable line fault locating on-line monitoring device. The distribution network cable line fault locating on-line monitoring device of the utility model solves the problem that there is not existed a device for on-line monitoring the running state of the cable power distribution network, and comprises a power distribution remote terminal and a system main station. The power distribution remote terminal comprises a cable short circuit fault detection terminal, a cable earth fault detection terminal, a grounding signal collector, a panel indicator and a cable type communication host, and the system main station comprises a router, a communication switch, a data server, a client and a monitor center server, wherein the signal output end of the cable short circuit fault detection terminal and the signal output end of the cable earth fault detection terminal are both connected with the signal input end of the panel indicator. The distribution network cable line fault locating on-line monitoring device of the utility model is suitable for the cable power distribution network.