The distribution system is commonly assumed to be balanced in the single-line-to-ground (SLG) fault analysis and ground-fault arc suppression. The existing arc suppression methods are poor in the case of an SLG fault in a distribution network with unbalanced ground parameters and load. To solve the above problems, a voltage-type arc suppression method considering line impedance and distributed parameter imbalance is proposed. The equivalent model of distribution network considering the distributed parameters imbalance of the distribution network and line impedance is analyzed, and the accurate voltage-type arc suppression reference is derived. The neutral voltage reference is calculated by injecting currents before and after the fault. The active arc suppression device regulates the zero-sequence voltage to the reference value, so as to suppress the fault voltage and current to zero. In order to avoid the increase of fault current caused by the arbitrary injection current, the traditional current-type arc suppression is used as the transition of voltage-type arc suppression. This can effectively compensate for the fault current. By comparing the existing voltage-type arc suppression method considering line impedance, the method ignoring line impedance and the proposed method, the simulation results show that the proposed method has the best arc suppression performance under different imbalance degree, fault location and grounding resistance.