Abstract: In order to improve the fusion quality of multi-spectral images and panchromatic images, after studying a variety of filters and fusion algorithms, a regional fusion method was proposed based on multistage guide filters. First of all, the new method was adopted to interpolate the multispectral image; then the improved watershed algorithm was used to divide the panchromatic image, and the result was mapped to each multispectral image. Secondly, a multistage guide filter was used to filter the multispectral image and the panchromatic image, and their details were obtained respectively. Finally, according to the local correlation coefficient and the 4-order correlation coefficient between the panchromatic image and multispectral image, the detailed information was fused and the fusion images were obtained. The results show that the algorithm retains the multispectral image spectrum information and at the same time, details of the panchromatic image were put into the fusion image as much as possible. The method improves the effect of multispectral image fusion.