Abstract: OBJECTIVE To study the IDO inhibitor of 1-methyltryptophan (1-MT) intervented on microglia activation and inflammatory factor expression on cerebral ischemia reperfusion rat. METHODS SD rats were divided into sham operation group, model group, and 1-MT group. The model of ischemia reperfusion was constructed by the middle cerebral artery occlusion (MCAO) method. The nerve function defect was scored in rats. Determination of cerebral infarction volume by TTC method. The pathological changes of infarct area were detected by HE staining. Immunohistochemical method was used to detect the expression of IBA-1 and GFAP in the infarct area. The number of NeuN positive cells was detected by immunofluorescence. The expression of IL-1β, NF-κB, TNF-α in the tissue was detected by Western blot. BV2 cells were cultured in vitro, and oxygen glucose deprivation(OGD) was used to simulate the conditions of ischemic and anoxia. The control group, model group and 1-MT group were set up. The expression levels of IBA-1, IL-1β, NF-κB, TNF-α were detected by Western blot. RESULTS 1-MT could significantly improve the neural function of MCAO rats, reduce the infarct size, inhibit the activation of microglia and the expression of related inflammatory factors. 1-MT could significantly reduce the IBA-1 expression of IBA-1, IL-1β, NF-κB and TNF-α in OGD-BV2 cells. CONCLUSION IDO inhibitor 1-MT has a good protective effect on the cerebral ischemia-reperfusion in rats, and its mechanism is related to the inhibition of microglia and the expression of related inflammatory factors.