In this paper, a small current ground fault line selection system model is established under Matlab/Simulink environment. By setting the line parameters and simulation parameters, the fault simulation of the neutral point through the arc suppression coil grounding mode is completed. The characteristics of the single-phase grounding fault of the neutral point through the arc suppression coil are analyzed, and the zero-sequence voltage and zero-sequence current simulation waveform diagrams of the non-fault line and the fault line are given. The principle of line selection by zero-sequence admittance method is analyzed, a simulation model is built, and line selection is simulated, and the correctness of the method is verified.