The invention provides a small current grounding system line selection method based on steady-state zero-sequence current comparison. In the method, as for a single-phase grounding fault type which often occurs in a distribution network, by comparing collected and uploaded steady-state zero-sequence current, in view of a neutral ungrounded system and an arc suppression coil grounding system, the steady-state zero-sequence current of each line and the steady-state zero-sequence current change amount of each line after one line is cut off are compared respectively, and the grounding fault line can thus be discriminated. According to the small current grounding system line selection method provided in the invention, the single-phase grounding fault in the distribution network can be effectively discriminated, and besides, the steady-state zero-sequence current is adopted for comparison, the grounding fault line can be quickly and accurately selected.