Obstructive sleep apnea syndrome （OSAS） is a common sleep breathing disorder， and chronic intermittent hypoxia （CIH） is the most important pathophysiological feature of it. In recent years， the research on CIH-induced cognitive impairment has become a hot spot. Research has found that CIH can activate microglia to cause neuroinflammation， release inflammatory factors， cause central nervous system damage， and further lead to cognitive dysfunction. This article reviews the ways in which CIH activates microglia， and the molecular mechanism of microglia's involvement in CIH-induced cognitive dysfunction， in order to provide support for further research.