To study the saponin from Albizia julibrissin.A saponin was separated by using chromatography and its structure was elucidated on the basis of spectral data.A saponin was obtained and it's structure was identified as 3-O-[beta-D-xylopyranosyl-(1-->2)-alpha-L-arabinopyranosyl-(1-->6)-beta- D-2-deoxy-2-acetamidoglucopyranosyl]-21-O-(6S-2-trans-2-hydroxymethyl- 6-methyl-6-O-[4-O-(6S-2-trans-2-hydroxymethyl-6-methyl-6-hydroxy-2, 7-octadienoyl)-beta-D-quinovopyranosyl]-2, 7-octadienoyl)-acacic acid-28-O-beta-D-glucopyranosyl(1-->3)-[alpha-L-arabinofuranosyl- (1-->4)]-alpha-L-rhamnopyranosyl-(1-->2)-beta-D-glucopyranosyl ester.The saponin is a new compound named Julibroside J6.