Postoperative cognitive dysfunction（ POCD） is an acute mental disorder with cognitive and attention impairment， which is closely related to central nervous system inflammation. However， its mechanism is still unclear. TREM2 is the trigger receptor for myeloid cells 2， and is expressed on microglia， dendritic cells and many other cells. TREM2-DAP12 is a complex specifically located on microglia and has anti-inflammatory and phagocytic effects. This article reviews the structure， physiological function of TREM2-DAP12 and the regulation of microglia on POCD and the research progress.