In the study of autofocus technology, it is always difficult to obtain the all-in focus images because of optical system’s limited focus depth, but a high definition image is very important to scientific research. In the research of autofocus technology, we know that detection of the focused region is the key issue of the multi-focus image fusion algorithm, the blurred boundary of the focused region increases the more difficulty of identifying focused regions accurately. Accord-ing to these principles, the focused region of the source image should be directly fused as much as possible.