Abstract: For advancing the fusion algorithm quality of multi-spectral and panchromatic images, an image fusion algorithm of multi-spectral and panchromatic images was presented by region mutual information. Firstly the multi-spectral image was turned to HSV color space, and region segmentation was applied to V component by the method of watershed and region combination, and spectral distance was taken as the region combination estimation. Secondly the V component of multi-spectral image and panchromatic image were decomposed multi-resolution by nonsubsample Contourlet transform(NSCT), the region segmentation was mapping to the panchromatic image, and the multi-resolution decomposition coefficient was fused by calculating the mutual information of corresponding region to obtain the decomposition coefficient of fusion image. Lastly the fusion image reconfiguration was realized through NSCT inverse transform. The experimental result shows that the image fusion algorithm presented by this paper retains the spectral information of multi-spectral image adequately, meanwhile injects details information of panchromatic image as much as possible, which advances the edge characteristic of multi-spectral image effectively.