The waveforms of transient zero sequence current before and after the fault point is obviously different when single-phase earth fault occurs in non-solid-earthed system, difference of amplitude distribution over a period of time is big. But waveforms of transient zero sequence current on the same side of fault point’s upstream and downstream is similar, and the difference of amplitude distribution over a period of time is small. The fault section is determined by similarity relations of the amplitude distribution of transient zero sequence current over a period of time after fault, and the difference coefficient of amplitude distribution is defined to characterize the similarity of amplitude distribution of transient zero sequence current in different testing points. Firstly, it calculates the amplitude difference coefficients of both sides of the testing point in every sections, and then, the fault section is determined by the corresponding maximum amplitude difference coefficient. The signals of transient zero sequence current can only be used in this method, and the fault signal is easy to obtain. Simply uploading the detection point amplitude distribution sequence, it has small data transmission. This work is supported by Fundamental Research Funds for the Central Universities (No. 16CX06051A).