Abstract: When an image is captured by optical sensor, some parts of the scene will be blur due to lost focus. Image fusion is a method for integrating multifocus images into a composite image which is more suitable for work. In order to fuse multifocus images, a new blind image quality assessment metric, Vision Structural Similarity (VSS), was first proposed in this paper. Based on this metric, multifocus image fusion problem could be described as an optimization process. Through optimizing source images by evolutionary computation, the image with best VSS value would be chosen as fusion result. The experimental results of the proposed method show high performance in both consistency and reliability comparing with other fusion schemes.