In the neutral point ungrounded system of the distribution network and the grounding system through the arc suppression coil, the traditional ground fault phase selection method does not consider leakage resistance and three-phase asymmetry. The phase selection error is caused when the transition resistance is high. Phase selection method based on phase difference for grounding faults in asymmetric distribution networks is proposed in the paper. Line leakage resistance and three-phase asymmetry parameters are considered in the paper. The intrinsic relationship between the phase difference between the fault phase voltage and the neutral point voltage change before and after the fault and the arc suppression coil compensation state and line parameters are analyzed. The ground fault selection criterion is obtained. Finally, the implementation scheme of phase selection method for grounding fault of distribution network is proposed. The grounding fault model of the distribution network is built in the PSCAD/EMTDC simulation environment. The simulation results show that the criterion is always applicable under different transition resistances and different arc suppression coil compensation states. The feasibility of the proposed method is verified.