To increase the amount of image information after fusion and improve image clarity, an improved image fusion algorithm based on the Red-Black wavelet is put forward. The PCA transform is performed to the source image before Red-Black wavelet transform. Then the multi-scale Red-Black wavelet decomposition is carried out to the obtained first component. For the high-frequency and low-frequency sub-band coefficient, the selection based on the maximum value and the fusion rule based on the regional variance are adopted respectively. The Red-Black reconstruction is carried out to the sub-images of each level after the fusion, and PCA reverse transform is carried out to the reconstructed results to obtain the fused images. The simulation results show that, the multi-spectral image fusion performed by the proposed algorithm can effectively preserve spectral information, has a high spatial resolution, improve the entropy, increase the amount of information of the fused images, and improve image clarity effectively with better visual effects. It has a wide application prospect in the field of remote-sensing image processing.