Image fusion is an important application in the field of image processing using multisensors information , and taking wavelet transform as a tool is a great breakthrough in research method of this fieldOn the basis of wavelet transform , the paper proposes a kind of multispectral image fusion algorithm after the study of area-based selection rule, and compares this algorithm with other algorithms in existence . The results show that this algorithm is not only simple and of high stability but effective in image enhancement , therefore it is a advisible algorithm in image enhancement.