In order to accurately locate the single phase ground fault point in the small-current grounding system, the fault location is transformed into comparing zero sequence current similarity based on transient recording fault indicator. The coding rules of each branch of power line are determined. A fault location algorithm is designed based on discrete mean distance. The experiment is carried out by simulating various ground faults that may occur in practice. The test results show that it is feasible to apply the method of comparing the similarity of zero-sequence current waveforms to the on-line monitoring field of distribution automation for ground fault location. This work is supported by Henan Provincial Science and Technology Project (No. 1821021479) and Key Research Projects of Henan Higher Education Institutions (No. 17A413010).