Among the existing synthetic-aperture radar (SAR) satellites, the GF-3 offers the most kinds of imaging modes. The fusion of the GF-3 SAR images with the multi-spectral images can improve the visual quality of the SAR images. We show how to use the nonsubsampled contourlet transform (NSCT) for simulating high-resolution images such that both the details of the SAR image and the spectral information of the multi-spectral image can be retained. This method ensures that the fusion of SAR and multi-spectral images is not limited by a specific algorithm. To verify the effectiveness of the proposed idea, two types of resolutions are used as the experimental data: the GF-3 satellite SAR images with resolutions of 3 m and 5 m, respectively, and the GF-1 satellite multi-spectral images with a resolution of 16 m. We perform comparative experiments with different fusion algorithms. The results show the effectiveness of the proposed approach. The traditional method that directly fuses the SAR and multi-spectral images can keep the details of the SAR image. However, the noise is obvious and some information of the multi-spectral image remains. The NSCT average images and the average NSCT images can retain the spectral information. The spectral information of NSCT average images is closer to the multi-spectral images than the average NSCT images.