Background　Elderly patients are more vulnerable to postoperative cognitive dysfunction (POCD). It can be featured as cognitive deterioration, attention disorder and reduced consciousness to the environment thus resulting in high morbidity and mortality.　Objective　To review the reported physiological and immunological changes and genetic factors, identify candidates for further studies and integrate the information systematically.　Content　This article aims to explore the biomarkers of POCD.　Trend　The pathogenesis of POCD is multifactorial; integrated application of system biology may be helpful to reconstruct the underlying molecular networks and identify potential prognostic and diagnostic biomarkers.