To explore the effect of luteolin on the immune balance of T helper 17 cells (Th17)/regulatory T cells (Treg) in a mouse model of ulcerative colitis (UC),and to analyze its underlying mechanism.Sixty BALB/c male mice were randomly separated into normal group,model group,positive control group,luteolin group,luteolin+3-TYP group,with 12 mice in each group.Dextran sodium sulfate (DSS) was performed to induce the establishment of a UC model,the weight change,stool consistency and stool occult blood in mice were observed and recorded,and the disease activity index (DAI) was calculated;HE staining was used to observe the histopathological changes of the colon;flow cytometry was used to measure the ratio of Th17 and Treg cells in the spleen,and the ratio of Th17/Treg was calculated;ELISA was used to measure the contents of IL-6,IL-10,IL-17 and IL-23 in colon tissue;RT-qPCR was used to measure the mRNA expression of RORγt and Foxp3 in colon tissue;Western blot was used to measure the expression of colonic tissue SIRT3,AMPK,p-AMPK,mTOR,p-mTOR proteins.Compared with the normal group,the DAI score,histopathology score,spleen Th17/Treg ratio,colon tissue IL-6,IL-17,IL-23,RORγt mRNA levels and p-mTOR/mTOR ratio of mice increased in the model group,the IL-10,Foxp3 mRNA and SIRT3 protein levels,and p-AMPK/AMPK ratio decreased (P<0.05).After drug intervention,the DAI score,histopathology score,spleen Th17/Treg ratio,colon tissue IL-6,IL-17,IL-23,RORγt mRNA levels and p-mTOR/mTOR ratio of mice decreased,the IL-10,Foxp3 mRNA and SIRT3 protein levels,and p-AMPK/AMPK ratio increased P<0.05);3-TYP was able to weaken the effect of luteolin on the differentiation balance of Th17/Treg cells in UC mice (P<0.05).Luteolin can improve Th17/Treg imbalance in DSS-induced UC mouse model,and its mechanism may be related to the activation of SIRT3/AMPK/mTOR pathway.