The invention discloses a method and a device for predicting a tree growth trend in a power transmission line area. The method comprises the following steps: acquiring a satellite remote sensing imageat least comprising a first area of the power transmission line area; performing image correction on the satellite remote sensing image to obtain a corrected image; extracting the tree reflectivity in the corrected image so as to obtain tree distribution information according to the tree reflectivity; fusing the tree distribution information of the corrected image with a power grid GIS to determine a target image, the target image being an image corresponding to the power transmission line area with tree distribution in the corrected image; and predicting the tree growth trend of the power transmission line area according to the tree reflectivity of the target image and a pre-acquired corresponding relationship between the tree growth trend and the tree reflectivity. The problems that according to an existing method for obtaining the tree growth situation in a patrol mode, time and labor are wasted, efficiency is low, and the tree growth trend cannot be predicted are solved.