In the resonant grounding system, the arc suppression coil only compensates for the power frequency zero-sequence current, and has almost no influence on the non-power frequency electrical quantity. When single-phase ground fault occurs, the fault lines are opposite to the zero-sequence current of the non-fault lines. In this paper, to determine the fault line, the Pearson correlation coefficient method is used to calculate the correlation coefficient of the first half-wave waveform of the zero-sequence 5th harmonic current between these distribution lines. The simulation results show that the correlation coefficient method is not affected by different factors.