Abstract: A new flavonol glycoside, C₂₇H₂₈O₁₀, mp 151～152℃( MeOH),named acuminatin (Ⅰ), was isolated from the aerial part of Epimedium acuminatum Franchin addition to four known compounds. By means of UV, FAB-MS, EI-MS,¹HNMR, ~(13)CNMR and chemical evidences, the structure of acuminatin was establishedas 6", 6" - dimethylpyrano (2", 3": 7, 8) 4' - methyl kaempferol- 3 - O - α - L -rhamnopyranoside. The known compounds were identified as kaempferol-3- O-α- L- rhamnopyranoside (Ⅱ), quercitrin (Ⅲ), hyperin (IV) and daucosterol (Ⅴ).