The flavonoids of Epimedium,namely icariin,epimedin A,epimedin B and epimedin C,were determined by HPLC.Combined with principal component analysis (PCA),the quality of different species of Epimedium was analyzed and evaluated. Moreover,the protective effect of Epimedium on kidney-yang deficiency in rats was also investigated.The experimental animals were randomly divided into yang deficiency model control group (model group),Jinkui Shenqi pill intervention group (positive group),Epimedium low (125 mg/kg),medium (250 mg/kg),high (500 mg/kg) dose group.Four weeks later,uric acid (UA),creatinine (CRE) and urea nitrogen (BUN) in serum of rats with kidney-yang deficiency were measured.The results of principal component analysis showed that principal component 1 icariin,epimedin C and principal component 2 epimedin B were the main factors affecting the quality evaluation of samples.The 12 batches of Epimedium medicinal materials were of good overall quality.The pharmacological results showed that compared with the blank group,the levels of UA,CRE and BUN in rat serum were significantly reduced.The above results indicated that the method measured four effective constituents of Epimedium flavonoids in the meantime,which provided a reference for establishing quality evaluation system of Epimedium;Epimedium has obvious protective effect on hydrocortisone-induced kidney-yang deficiency and has a dose-effect relationship.