Chemical constituents of the whole herb of Bidens pilosa L. were investigated. By using various column chromatography （CC） and spectroscopic methods, 13 flavonoids were isolated and identified as follows： 2′-hydroxy-4,4′-dimethoxy-chalcone （1）, isoliquiritigenin （2）, 3,2′,4′-trihydroxy-4-methoxy-chalcone （3）, licochalcone A （4）,4′-O-β-D-glucopyranosyl-2′,3-dihydroxy-4-methoxy-chalcone （5）, butein （6）, apigenin （7）, luteolin （8）, diosmetin （9）, chrysoeriol （10）, 3,5,6,7,3′,4′,5′-heptamethoxyflavone （11）, 7-O-β-D-glucopyranosyt-5,3′dihydroxy-3,6,4′-trimethoxyfiavone （12）, sulfuretin （13）. Compounds 1-5, 9, 11 were obtained from the genus Bidens for the first time.
