Nine sesquiterpenoids,including three guaiane-type (1,2 and 9),three eudesmane-type (4-6) and three germacrane-type (3,7 and 8),were isolated from MeOH extract of the rootstock of Saussurea lappa C.B Clarke by silica gel and Rp18 column chromatography,as well as semi-preparative high performance liquid chromatograph.The compounds were identified as dehydrocostus lactone (1),sausinlactone A (2),costunolide (3),α-cyclocostunolide (4),β-costic acid (5),reynosin (6),picriside B (7),saussureamines A (8) and B (9) by NMR and Mass spectroscopy.Among them,compounds 8 and 9 were unnormal aminoacid-sesquiterpene lactone conjugates.The MTT method was used to test cytotoxic activity of compounds 1,3,4,6,8 and 9 against liver cancer cell lines (HepG2).These compounds showed weak inhibit activity against HepG2 liver cancer cell lines at a concentration of 30 μM.Among them,the inhibit activity of compound 3 was more than 60%.