In order to extract the information of transmission corridor from satellite images, a method based on the highresolution remote sensing image No. 2 is proposed. Firstly, the weighted grayscale transformation based on lowresolution multispectral images is applied to obtain binary images. The information of transmission lines and towers is extracted by image edge detection and line detection methods. Then, the fused highresolution images are identified by the minimum distance method, and the vegetation coverage index is calculated. Finally, the transmission line is reconstructed in the vegetation distribution image, and the vegetation coverage index is utilized to warn the vegetation threatening areas. The simulation results show that the recognition rate of pole and tower extraction from binary image by edge detection is 100%, the contour of the fused vegetation distribution image is clear, and the recognition accuracy of vegetation coverage area is over 90%. Combined with the vegetation coverage index, the early warning area has dense vegetation growth, which threatens the safe operation of transmission lines. The proposed method realizes the early warning of vegetation growth in the transmission corridor, and can be applied in the transmission safety online monitoring of power industry.