Abstract:Total flavonoid contents and antibacterial activities of the extracts ofAcanthopanax trifoliatus（L.）Merr leaves were investigated.The powder of leaves were extracted with 95%EtOH.After the solvent were evaporated，the resultant extract was then extracted in turn with petroleum ether，chloroform，ethyl acetate，n-BuOH and water.The contents of total flavonoid of the extracts were measured by the standard curve method.The antibacterial activities of the extracts were measured by using minimum inhibiting concentration method against eight bacteria，such asE.coli，Salmonella，S.aureus.The result indicated that the highest content of flavonoid was 282.39 mg/g in the ethyl acetate extract.The petroleum ether extract had the best antibacterial activity.The extract from petroleum ether exhibited higher inhibition effect toSalmonella，E.coli，S.aureus，White staphylococcusandMicrococcus luteuswith a MIC range of 10 μg/mL to 40 μg/mL and lower inhibition effect to bacillus.The correlation bettween the content of total flavonoid and antibacterial activity was existed but not a simple proportional relationship.