Abstract: The correctness of fault phase selection is one of the core technologies of the full compensation arc suppression technology in distribution network for single-phase earth faults. At present, fault phase selection is mainly used for single-phase automatic reclosing and distance protection algorithms in effectively grounded systems. These methods have applicability problems in single-phase grounding faults of non-effectively grounded distribution networks. This paper proposes a new phase selection method based on the characteristics of the three-phase voltage and current before and after the change of the injected current based on the arc-extinguishing device consists of the active inverter, thereby promoting the project implementation of the full compensation arc suppression system using in the distribution network.