A new tetranortriterpenoid, named 6-deacetyl-severinolide, together with six known tetranortriterpenoids severinolide, acetyl-isoepiatalantin, 7-isovaleroylcycloepiatalantin, cycloepiatalantin, 7-isovaleroylcycloseverinolide, and atalantin, was isolated from the ethanol extract of the roots of Atalantia buxifolia collected in Hainan. Their structures were elucidated by spectroscopic methods including 1D and 2D NMR (HMQC, ¹H-¹H COSY, HMBC, and NOESY).