The increasingly importance has been attaching to postoperative cognitive dysfunction (POCD), a post operative complication of the central nervous system. However, the study conclusions of POCD are different totally due to lack of uniform methodology, cohesive definition and diagnosis criterion. This article reviews the measurement techniques and diagnosis criterion in detecting postoperative cognitive function from departed POCD studies both at home and abroad and provides reference for establishing consensus of diagnosis parameters of POCD and discerning POCD correctly.