Abstract: In this paper, image features are analyzed for high voltage transmission lines under various circumstances and then a method combining LoG operator and morphology is proposed. The gray image histogram shows that this method can not only present two peaks well, but also exhibit better performance finding the optimal threshold segmentation points. Compared with the improved Otsu (maximal variance between clusters) image segmentation algorithm, this method makes it easier to separate the target from the background. Matlab simulation results show that the proposed method can successfully detect the contour edge of the target in the image regardless of environment impact of high voltage transmission lines. It is still effective even under the influence of certain severe natural environment conditions.