Abstract: Through the analysis of the increase of the line loss of the 10kV distribution line, the main reasons for the increase of the line loss caused by harmonics are described. It is the skin effect of the line conductor that makes the harmonic resistance larger than the fundamental wave resistance, causing additional losses in the winding (or line conductor) to increase. The effectiveness of the method of suppressing harmonic wave line loss from design, management and technology is discussed, and the corrective measures for adding a zero-sequence filter reactor on the neutral line are proposed. Harmonic-induced network losses, in addition to the direct increase in line loss caused by harmonics, will also cause a decrease in the power factor, which indirectly leads to an increase in the loss of the wire.