Abstract: The traditional harmonic responsibility division method is difficult to be fully immune to the variation of background harmonics and harmonic impedance of power system, and lacks the overall consideration of harmonics at different orders. To solve the above problems, according to the mechanism of harmonic generation, a harmonic responsibility division index based on load equivalent impedance parameters is proposed. The index can quantify the harmonic responsibility of each feeder under a single bus. Furthermore, a two-point load impedance parameters estimation method is proposed for three-phase symmetrical load that avoids the problem of abnormal value caused by zero crossing of denominator, which lays an application foundation for harmonic responsibility division. The feasibility and effectiveness of the proposed index and method are verified by example calculations.