Background More and more attention has being paid to the disadvantage of postoperative cognitive dysfunction（POCD）, especially in elderly. Currently, functional magnetic resonance imaging （fMRI）is a powerful, noninvasive research method which can be widely used in the field of cognitive neuroscience. Objective The purpose of this review is to discuss recent development in the pathogenesis and diagnose of POCD. Content Discuss the diagnosis, pathogenesis of POCD associated with coronary artery bypass surgery and fMRI in diagnose POCD. Trend There are many factors leading to POCD, but the etiology and pathogenesis is not clear yet. An effective means of prevention is particularly important.