A method of steady state of a small current grounding line selection is proposed in this paper, which take full advantage of distribution network single-phase grounding fault of fault line and non fault line"s zero sequence current and zero sequence voltage phase relationship, with the existing distribution automation technology, novel in meter and the influence of distribution line resistance, consider the line under a load line fault and non fault line zero sequence current and voltage phase relationship, and through in the feeder automation terminal unit (FTU) embedding phase DFT detection algorithm to detect zero sequence current and voltage phase difference. The simulation proves the effectiveness of fault line selection method..