Abstract: The length of the transmission line is affected by load flow, environment, and other factors, and the error of fault location using fixed line length is significant. Based on binocular vision technology, this paper analyzes and processes the image information of transmission lines and proposes a high voltage transmission line length correction method applied to traveling wave fault location. Firstly, according to the calculation formula of transmission line length, the parameter determining the actual line length is defined as the strain ratio coefficient; Secondly, for the collected line image, through the steps of epipolar correction and edge detection, the visual difference of pixels in the whole image is calculated, and the spatial three-dimensional coordinates of several feature points on the transmission line are restored according to the binocular vision model; Finally, the coordinates of feature points are fitted, and the specific coefficient is updated into the catenary length calculation formula to obtain the transmission line length in the actual environment, which is then applied to the double ended traveling wave method for accurate positioning. According to the image expansion example of a 500kV transmission line in a practical project, the traveling wave fault location process is simulated by PSCAD/EMTDC. The simulation results show that the proposed method can effectively reduce fault location errors and is helpful in the rapid removal of faults.