Abstract: In this paper, several cases of voltage waveform distortion in distribution network are analyzed, and the energy spectrum of each phase resonance is calculated by MATLAB. Spectral analysis shows that the maximum energy of each phase voltage except the fundamental wave is basically the same as the waveform frequency in the zero-sequence voltage. Moreover, multiple voltage waveform distortions occur after the ground fault cutting off, which instruction that the distortion of the voltage waveform is most likely due to the resonance between the line capacitance and the arc suppression coil. According to the follow-up tracking of actual operation of the arc suppression coil, it was found that the arc suppression coil is actually operating at the limit position. The system is actually operates in the fully compensated position. Finally, the RTDS simulation system is used to modeling this situation, the simulation results are basically consistent with the actual recorded waveforms, verifying the correctness of the analysis results of this paper.