With the continuous development of the economics， the customer demand for reliable power supplies is increasing. An on-line fault location method is proposed for the single phase to ground fault in the distribution network. First， the faulty area is identified by inquiring the current transformers installed nearby the sectionlised switches， and transmitting the measurements to the main station through wireless communication networks， then judging the faulty region by analyzing the measured currents and the structure of the distribution network; second， the special fault spot is identified by detecting the magnetic field of fundamental frequency signals， without additional signals. ATP simulation and experimental results prove the presented method correct and effective.