The invention discloses a power distribution network single-phase earth fault on-line monitoring and positioning system. The power distribution network single-phase earth fault on-line monitoring and positioning system includes a line measuring unit, a power distribution network monitoring main station and a data base station, wherein a wireless communication module of the line measuring unit utilizes bluetooth short range wireless networking modules, and is connected with bluetooth short range wireless networking modules contained in the data base station through the bluetooth short range wireless networking modules; and the data base station is connected with the power distribution network monitoring main station through a GPRS remote wireless communication module. The power distribution network single-phase earth fault on-line monitoring and positioning system has the advantages of high transmission speed, long transmission distance and low possibility of data loss in the data transmission aspect, and can bring great economic benefit. The power distribution network single-phase earth fault on-line monitoring and positioning system is suitable for performing on-line monitoring and positioning on a single-phase earth fault of a power distribution network.