To explore the mechanism of Gegenpeifang Granules in benign prostatic hyperplasia of mice.Methods:Sixty male mice from Kunming,all four weeks of age,were randomly divided into 6 groups,including Gegenpeifang Granules 10,20,30 mg/Kg groups,a control group (finasteride) 1 mg/Kg,a model group and a normal group.Except a normal group,mice of other groups were given testosterone propionate 5 mg / kg / d by subcutaneous injection at 7 days after surgical castration.Different dose of Gegenpeifang Granules and finasteride were given by gavage for 3 three weeks.After that,mice were broken neck to death and their prostates were weighed and prostate index (PI) was calculated,detecting the expression of FGF2,Ki67,TGF-β1 by immunohisochemical method and 5a-reductase activity by ELISA,the apoptosis index by TUNEL kit.Results:Comparing with the model group,other groups had a signify-cantly reduce of prostatic volume,prostatic index,FGF2,Ki67,TGF-β1,5 a-reductase（P<0.05）,while had a higher apoptosis index（P<0.05）.There had no statistical difference between kudzu root20、30 mg/Kg groups and finasteride group（P>0.05）.Conclusion:The Gegenpeifang Granules may shrink prostatic volume of mice by reducing the activity of 5a-reductase,inhibiting the expression of FGF2，Ki67，TGF-β1,promoting cell apoptosis,and thus straining prostatic volume of mice.