Object In order to control the quality of crude drug, the total flavonoids of Epimedium koreanum Nakai were investigated Methods By repeated chromatographic methods 13 compounds were isolated and purified, and their structures were elucidated by physicochemical properties and spectroscopic methods (UV, IR, 1HNMR, 13 CNMR, HMBC, EI MS) Results They were identified as icariside II (Ⅰ), icariside I (Ⅱ), epimedoside C (Ⅲ), epimedin B (Ⅳ), icariin (Ⅴ), hyperoside (Ⅵ), hexandraside E (Ⅶ), anhydroicaritin (Ⅷ), maltol (Ⅸ), demethylanhydroicaritin (Ⅹ), insistol (Ⅺ), epimedoicarisoside A ( ⅩⅡ ) and (+) cycloolivil ( ⅩⅢ ) Conclusion Compounds Ⅶ, Ⅺ, ⅩⅢ were isolated from E koreanum for the first time, and Ⅶ was obtained from the plants of Epimedium L for the first time