A new frame of multi-resolution singular value decomposition (MSVD) was presented and applied into multi-focus image fusion. Based on the principle of blocking algorithm, images involved in fusion were decomposed into one approximation and three detail images with different resolution by singular value decomposition. Combined with reconstruction algorithm of MSVD, the frame of image fusion was given. Compared with image fusion by discrete wavelet transform (DWT), image fusion by MSVD performs better. Moreover, MSVD does not have a fixed set of basis like wavelet, and its basis vectors depend on the image itself. The performance of the result image was evaluated using objective indices. The experimental result shows that not only the proposed method is simple, but also that the visual effect of the image is considerable after reducing blocking artifact. And both the definition and spatial frequency are improved greatly.