When a single-phase ground fault takes place in small current grounding system with neutral point grounding through the arc suppression coil, namely a resonant grounding system, the charge-voltage relationship of sound feeder and faulty feeder in fault transient time is analyzed. This characteristics’ performance under various working conditions such as different grounding resistance, different fault distance, mixed lines and noise is analyzed by simulation. The results show that the zero-sequence charge is linear with the zero-sequence voltage in sound feeders while there is no linear relationship in fault feeders. In addition, these characteristics of the charge-voltage relationship can be used to distinguish sound feeder from faulty feeder rapidly and evidently. It provides an effective basis for the line selection.