Abstract: Objective:To study the regulating effect of gymnemic acid on blood lipids of high-fat hamsters and the mechanism of gymnemic acid regulating blood lipids. Methods:Forty male hamsters were randomly divided into normal control group,model control group and low(20 mg/kg BW/d),medium(40 mg/kg BW/d)and high dose group(80 mg/kg BW/d).The normal control group was fed with normal diet,while the other groups were fed with high fat diet for 8 weeks.Weight was weighed every two weeks and blood was taken from orbital vein every four weeks to detect serum lipid levels in hamsters at different stages. After eight weeks,femoral artery blood was taken to detect liver injury indicators such as glutamic oxaloacetic transaminase(AST),alanine transaminase(ALT),cholesterol metabolism-related regulatory enzymes such as hydroxymethyl glutarate monoacyl coenzyme A reductase(HMGCR),cholesterol 7alpha hydroxylase(CYP7A1),and activity of sterol acyltransferase(ACAT).The hepatic lobules were taken to detect the activity of HMGCR in the liver.Results:Before intervention,there was no significant difference in serum total cholesterol(TC),triglyceride(TG)and non-high density lipoprotein cholesterol(non-HDL-C)levels among the groups(P>0.05).After eight weeks of intervention,the levels of TC,TG and non-HDL-C in serum of hamsters in the dosage group were significantly lower than those in the model control group(P<0.01).The levels of ALT and AST in the dosage group were significantly lower than those in the model control group(P<0.05).The activity of HMGCR in the medium and high dose group was significantly lower than that in the model group(P<0.05).The activity of CYP7A1 in the medium and high dose group was significantly higher than that in the model group(P<0.05).Conclusion:Gymnemic acid can decrease the synthesis of cholesterol in high-fat hamsters by inhibiting the activity of HMGCR,increase the activity of CYP7A1 to increase cholesterol excretion,and regulate the level of blood lipid in high-fat diet hamsters. Therefore,gymnemic acid has the function of reducing lipid and protecting liver.