We present a novel fusion method to improve the spatial resolution of multispectral (MS) images, where the fused spectral images integrate the spectral information and spatial details from the original MS images and panchromatic (PAN) image, respectively. Band by band, a spectral image with high resolution is reconstructed from the original spectral image to take advantage of super-resolution technology. The pan-sharpening method via Amélioration de la Resolution Spatiale par Injection de Structures concept is further applied to obtain the fused images from the reconstructed spectral images and PAN image. Performance of the proposed method has been evaluated on the public optical satellite QuickBird images. Experimental results show that the fused spectral images both preserve the spatial details of high-resolution from the PAN image and have higher spectral resolution than the original spectral images.