OBJECTIVE:To investigate the saponin constituents of the root bark of Aralia taibaiensis, a new species.METHODS:Saponins were separated by HPLC and rechromatography on silica gel, whose structures were determined byspectral analysis and chemical evidence. RESULTS:Three saponins were obtained and elucidated as oleanolic acid-28-O-β-D-glucopyranoside(Ⅰ)，3- O-(6‘一O-butyl-β-D-glucuronopyranosyl)-oleanolic acid-28-O-β-D-glucopyranoside( Ⅱ)and 3-O-(6‘一O-decyl-β-D-glucuronopyranosyl)-oleanolic acid-28-O-β-D-glucopyra-noside( Ⅲ).CONCLUSION: Saponin I wasisolated from the plant for the first time. Ⅱ and Ⅲ are new compounds and named taibaienoside Ⅳ and taibaienoside Ⅴ，respectively.