Abstract: Objective To clarify the anti-oxidative role of Radix Astragali and its effect on angiotensin（Ang）1-7specific receptor,Mas,in metabolic syndrome（MS）rats. Methods A total of 120 male SD rats were divided into three groups:the normal control（NC）group,the MS group and the MS+Radix Astragali group MS+RA,6.0mg/（kg·d）in gavage. The two-kidney,one-clip method with high-fat diets and fructose water was constructed to mimic the MS model. After four-week treatment,hemodynamic and echocardiographic parameters were used to assess left ventricular functions. Plasma and myocardial AngⅡ,malondialdehyde and superoxide demutase（SOD）levels were measured with radioimmunoassay. The protein levels of Mas,angiotensin converting enzyme（ACE）and ACE2 were detected by Western blots. Results Compared with the NC group,systolic and diastolic pressure,body weight,fasting glucose,fasting insulin,triglycerides,free fatty acid,AngⅡ and myocardial malondialdehyde levels（30.37±7.43）and（22.43±5.25）vs（17.56±2.49）mmol/g)were significantly increased in both MS and MS+RA groups（all P＜0.05）,while myocardial SOD activity was decreased（106.34±16.07）and（141.06±23.20）vs（174.02±20.52）U/mg,P＜0.05. Plasma Ang Ⅱ and myocardial malondialdehyde levels were lower in the MS+RA group than in the MS group（P=0.001 and 0.017,respectively）,while myocardial SOD activity was higher（P=0.006）. Left ventricular internal pressure ±dp/dtmax was higher in the MS+RA group than in the MS group（both P＜0.05）. In myocardial tissue,ACE protein expression was increased in the MS group compared with the NC group,while ACE2 and Mas receptor expressions were decreased（all P＜0.05）.Compared with the MS group,ACE protein expression in myocardial tissue was decreased,while ACE2 and Mas receptor expressions were increased in the MS+RA group（all P＜0.05）. Conclusion Radix Astragali can increase the ACE2 and Mas receptor expressions,which has implications for new therapeutic in metabolic syndrome.