Abstract: Fault location of distribution network is one of the key technologies for power system. Aiming at the problem of fault location precision of distribution network effected by line parameters, the paper put forward a malfunction zone location means of distribution network of single power based on double-end impedance method on the basis of analyzing knowledge foundation for fault location. It also deduced the range measurement equation of single-phase grounded fault without branch in line of distribution network, supplying knowledge foundation for distribution network with multibranch. MATLAB simulation results showed that the method is effective.