To study the antihyperlipidemia effective constituent of Polygala fallax Hemsl.Column chromatographic techniques were employed for isolation and purification of chemical constituents of the plant and the structures were elucidated by IR, NMR and MS spectroscopy.Four triterpenoid saponins were isolated and determined as 3-O-beta-D-glucopyranosyl-( 1--> 2) -beta-D-glucopyranosyl presenegenin 28-O-beta-D-xylopyranosyl-(1-->4 ) -alpha-L-rhamnopyranosyl-(1-->2 ) -beta-D-fucopyranosyl ester (I), 3-O-beta-D-glucopyranosyl-(1-->2) -beta-D-glucopyranosyl presenegenin 28-O-beta-D-xylopyranosyl-(1-->4) -alpha-L-rhamnopyranosyl-(1-->2) -(3-O-acetyl)-beta-D-fucopyranosyl ester (II), 3-O-beta-D-glucopyranosyl-(1-->2) -beta-D-glucopyranosyl presenegenin 28-O-beta-D-xylopyranosyl-(1-->4) -alpha-L-rhamnopyranosyl-(1-->2) -(4-O-acetyl) -beta-D-fucopyranosyl ester (II) and 3-O-beta-D-glucopyranosyl-(1--2) -beta-D-glucopyranosyl presenegenin 28-O-beta-D-xylopyranosyl-(1-->4 ) -alpha-L-rhamnopyranosyl-(1-->2 ) - (3,4-diacetyl) -beta-D-fucopyranosyl ester (IV).The effective constituents of Polygala fallax Hemsl. reduced blood lipid especially plasma TG markedly. The authors have studied the chemical constituents of effective constituent systematically for the first time.