Aim To study protective effect and the anti-oxidize mechanism of Astragaloside on viral myocarditis in mice with CVB3. Methods Fifty Balb/c mice were randomized into five groups(n=10): normal control group,given 0.1 mL of EMEM by intraperitoneal injection,were teated with saline 0.1 mL with gavage after 30 minities of injection for 1 week;viral myocarditis Control group,inoculated intraperitoneally with 0.1 mL of 1×102 TCID50 CVB3 diluted in Eagle's minimal essential medium(EMEM) solution were given saline 0.1 mL with gavage after 30 minities of injection for 1 week;Astragaloside lowdose intervention group,middle-dose intervention group and high-dose intervention group,inoculated intraperitoneally with 0.1 mL of 1×102 TCID50 CVB3 diluted in Eagle's minimal essential medium(EMEM) were treated with 1%,3% and 9% astragaloside 0.07,0.2 and 0.6 g/(kg·d),respectively] 0.1 mL solution after 30 minetes of injection,respectively with gavage for 1 week.Survival number,score of pathological changes,GSH-PX,CAT,SOD and CuZn-SOD-mRNA of myocardium were detected. Results The survival number was significantly improved in Balb/c mice treated with high dose astragaloside group than that in viral myocarditis control group(P<0.01).Heart function was better in high-dose intervention group than in the viral myocarditis control group,the activity of GSH-PX,CAT,SOD and CuZnSOD -mRNA levels was enhanced and heart function was improved in group high dose astragaloside group than in viral myocarditis control group(P<0.01). Conclusion The results showed that astragaloside can provide protection against viral myocarditis.This protective effect of astragaloside may be related to the maintenance of the antioxidant status of the heart in improving myocardial antioxidant enzymes activity .