The utility model discloses a fault positioning and diagnosing system for a power distribution network. The fault positioning and diagnosing system comprises a computer, Ethernet, a communication front-end processor, a GPRS network, a plurality of concentrators, a plurality of first fault indicators and a plurality of second fault indicators, and each first fault indicator is corresponding to one concentrator. The computer and the communication front-end processor are connected to the Ethernet. The communication front-end processor is wirelessly connected to each concentrator by the GPRS network. Each first fault indicator is wirelessly connected to the corresponding concentrator. Each second fault indicator is subordinated to one of the first fault indicators, and is wirelessly connected to the first fault indicator directly, or is indirectly connected to the first fault indicator by another second fault indicator subordinated to the first fault indicator in a manner of wireless cascading. The fault positioning and diagnosing system provided by the utility model arranges the fault indicators in the manner of wireless cascading, and carries out real-time monitoring of the power distribution network. Compared with a wired fault indicator arrangement method, the wireless fault indicator arrangement method of the fault positioning and diagnosing system enables the cost to be reduced greatly.