The invention relates to the field of line loss calculation, more particularly to an influence weight analysis method for the line difference losses by harmonic and voltage deviations. Electrical parameters of an overhead line are collected and a line loss model under the harmonic single-item power quality indicator influence is established, wherein the model is a model I. A line loss model undera single-item power quality indicator influence of the voltage deviation is established, wherein the model is a model II. A line loss model under double-item power quality indicator influence of theharmonic and voltage deviation is established, wherein the model is a model III. The loss of the model I is added to the loss of the model II and the loss of the model III is subtracted from the sum to obtain a difference loss; and then weight analysis calculation affecting the difference loss is completed by an entropy method. According to the invention, the main factors and influence mechanism of the harmonic and voltage deviation on the overhead line energy consumption influence are systematized and the models are established to quantify the impact results, so that the energy consumption ofthe overhead line can be reflected objectively and truly and thus the reliable base is provided for energy conservation and consumption reduction.