Objective: To study the active chemical constituents of Siegesbeckia glabrescens

and find the target compounds with the function of inhibiting programmed cell necrosis. Method: The ethyl acetate extract fractions were isolated and purified by normal phase silica gel column chromatography (dichloromethane-methanol

20:1-0:1)

reverse phase ODS column chromatography (30%-100% methanol solution)

Sephadex LH-20 column chromatography and recrystallization; and their structures were determined according to physicochemical properties and spectral analysis. Result: Nine flavonoids were isolated and identified as 3

4-dimethoxy-2'

4'-dihydroxy chalcone (1)

7-O-(β-D-glucopyranosyl)-galactin (2)

7

3'

4'-trihydroxy flavone (3)

5

6

7

3'

4'

5'-hexamethoxyflavone (4)

8

3'

4'-trihydroxy-7-methoxy flavanoe (5)

5

4'-dihydroxy-7

3'-dimethoxy flavanoe (6)

7

4'-dihydroxy-3'-methoxyflavanone (7)

luteolin (8)

and quercetin (9). Conclusion: Compounds 1-7 were isolated from this plant for the first time.