Background　Post-operative cognitive dysfunction (POCD) happens at a higher incidence rate in elderly patients. Microglia is a kind of glial cell in central nervous system (CNS), which plays an important role in both the physiological and the pathological processes in CNS. A growing number of studies have demonstrated that microglia is involved in the development of multiple neurodegenerative diseases.　Objective　To review and discuss the role of microglia in the formation of POCD.　Content　In this review, we make a summary on the regulatory effects of microglia on learning and memory as well as on correlations between microglia and POCD.　Trend　The function of microglia in POCD is still not elucidated. Further in-depth research in this field may provide new ideas for the prevention and the treatment of POCD.