Microglia are important immune cells in the central nervous system. They play a dual role in inflammatory damage and neuroprotection during inflammatory response after cerebral ischemia. After cerebral ischemia,microglia are activated and prolifer-ated,converting into M1 phenotype and M2 phenotype. Different microglia phenotypes have different effects on cerebral ischemia. M1-polarized microglia inhibit the recovery of central nervous system by releasing inflammatory mediators,while M2-polarized microglia promote tissue regeneration and repair by releasing anti-inflammatory cytokines,transforming growth factor,and brain-derived nerve growth factor. This article reviews the activation and mechanism of action,migration and proliferation,polarization,and the effect of microglia on cerebral ischemia.