In consideration of the problem of high-resistance grounding fault line selection and section location in asymmetric distribution networks, a fault line selection and section location method for asymmetric distribution networks based on the fast switch arc suppression device is proposed. Firstly, the basic principle of the fast switch arc suppression device is analyzed. On this basis, the electrical quantity properties of each feeder in the distribution system prior to and following the operation of the device are analyzed in depth after the high-resistance grounding fault occurs in the system. Through theoretical derivation, it is found that the fault feeder and the non-fault feeder before and after the operation of the device differ in the variation of the zero-sequence equivalent admittance. Based on this, the fault feeder identification function is established, and the line selection and section location criteria are constructed. The proposed method is verified by PSCAD/EMTDC simulation software. The results show that the proposed method can accurately identify high-resistance grounding fault feeders and sections and is not affected by the three-phase imbalance of the distribution network.