Elderly patients are more vulnerable to postoperative cognitive dysfunction (POCD) which clinical features include cognitive deterioration, attention disorder and reduced consciousness of the environment. It can lead to more postoperative complications, longer hospital stays, lower quality of life, increased medical costs, and even increased mortality in elderly patients. In recent years, people are trying to find the ideal biological markers of POCD in order to reduce the occurrence of POCD. This review summarized the various known biomarkers of POCD and integrate possible factors for future studies so as to provide evidence for prevention, diagnosis and treatment of POCD. In this review, preoperative predictive biomarkers and postoperative diagnostic biomarkers were classified to explore the biomarkers of POCD. The pathogenesis of POCD is complex and diverse. Further studies are needed to identify predictive and diagnostic biomarkers and to provide effective preventive and diagnostic measures for the clinic.