Provided is an image fusion method, device and unmanned aerial vehicle. The method comprises following steps: performing bit plane layering on an original image of a frame to obtain a plurality of bitplanes of the original image, wherein the bit number of the original image is M, and M is an integer greater than 1; obtaining a plurality of frames of reconstructed images according to a plurality of bit planes, wherein the bit planes corresponding to different reconstructed images are not identical, and the bit number of each reconstructed image is N, and N is a positive integer smaller than M;fusing multi-frame reconstructed images to obtain a fused image of the original image. As the multi-frame reconstructed images directly come from the same frame image, thus ensuring the consistency of the image scene, it can be directly applied to exposure fusion without image registration, and the resulting fusion image will not contain ghost images. Compared with the prior art, the invention can avoid image blurring conveniently, highlight darkness and highlighted details at the same time, on the other hand, can reduce the algorithm resource overhead of image fusion.