The technology of image fusion is one of the most important technologies in digital image process. It has been applied to many fields such as military affairs, remote sensor, computer vision, medical image process and so on. Now there are many approaches in image fusion such as Weighted Averaging Algorithm, Contrast Modulation Algorithm, Toet Algorithm and Wavelet Transform Algorithm and so on. In this paper, a new algorithm for image fusion based on Point Spread Function (PSF) is presented and applied to medical images, the result is satisfying. By comparison, we find that the Algorithm based on PSF is suitable for image fusion.