Objective:To investigate the protective effect of quercetin(QUE)on acute lung injury(ALI)rats with sepsis.Methods:Sixty male SD rats were randomly divided into 6 groups(n=10):Sham operation group(Sham),model group(CLP),QUE 25 mg/kg group,QUE 50 mg/kg group,QUE 100 mg/kg group and positive drug dexamethasone(DEX)group.Rats in each group were continuously treated for 7 days,and the survival rate was calculated;HE staining and lung wet-to-dry weight ratio(W/D)were used to evaluate the severity of lung injury;TUNEL staining was used to detect lung tissue apoptosis;levels of inflammatory factors,SOD and MDA were detected by the kits;Western blot was used to detect expressions of apoptosis-related proteins and phosphoryla-tion levels of PTEN,β-catenin,protein kinase B(AKT)and glycogen synthase kinase-3β(GSK-3β)in rat lung tissue.Results:Com-pared with CLP group,after QUE 50 mg/kg and 100 mg/kg treatment,survival rate of rats was significantly increased(P<0.05),the degree of inflammatory cell infiltration in lung tissue was reduced,lung injury score and W/D were reduced(P<0.05),apoptosis rate of lung tissue cells and expressions of apoptosis-related proteins were significantly decreased(P<0.05),levels of inflammatory factors were decreased(P<0.05),while the antioxidant capacity was enhanced(P<0.05),phosphorylation levels of PTEN and β-catenin were decreased,while phosphorylation levels of AKT and GSK-3β were increased(P<0.05).Conclusion:QUE protects rats from ALI with sepsis by inhibiting apoptosis,reducing inflammation and antioxidance,which mechanism may be related to PTEN/β-catenin and AKT/GSK-3β pathways.