The invention discloses a filth component analysis-based path selection method for a power transmission line. The method comprises the steps of selecting points for suspending insulators from a proposed via area of the line and carrying out collection of natural filths; testing equivalent salt deposit density and dust density of the natural filths; carrying out soluble ion component analysis on the natural filths; selecting corresponding salts to combine with kieselguhr according to ion component analysis results to form simulated filths; coating a certain area of composite insulator surfaces with quantitative simulated filths to detect the hydrophobicity and the hydrophobicity transference; and coating a certain area of composite insulator surfaces with the quantitative simulated filths and carrying out flashover test on a test specimen to obtain flashover voltage. The hydrophobicity detection results and the filth flashover voltage results of the filths in different sections are compared, the filth which has relatively high hydrophobicity and relatively high filth flashover voltage is selected, and the section with the filth is the recommended via area of the line. According to the filth component analysis-based path selection method for the power transmission line, the pollution degree of the line path can be comprehensively evaluated and the operation reliability of the line is improved.