The invention discloses a power transmission line extraction algorithm under a complex background based on a Chebyshev polynomial descriptor. The algorithm comprises the following steps of carrying out preprocessing on an input image; using random Hough conversion to extract a straight line and a curve in the image; using a curve description advantage of the Chebyshev polynomial descriptor to carry out characteristic description on an extracted object; through a K-means cluster analysis method, training visual dictionaries; and through comparison of the visual dictionaries, extracting a power transmission line in the image. In the invention, precision of power transmission line extraction under the complex background can be effectively increased.