The invention discloses an icing detection method and system for inspecting an overhead transmission line based on an unmanned aerial vehicle. The method comprises the steps of obtaining a video shotin the process of inspecting the overhead transmission line by the unmanned aerial vehicle; extracting a key frame image from the video; processing the key frame image to respectively obtain a gray image, a contour image and a texture image; extracting gray features of the gray image, contour features of the contour image and texture features of the texture image; carrying out normalization on theextracted gray features, contour features and texture features, performing series fusion on the gray features, contour features and texture features after normalization processing, and acquiring fusion features; and inputting the fusion features into a pre-trained convolutional neural network model, and outputting a classification result about whether icing occurs or not.