Abstract: AimTo study the active constituents for the treatment of rheumatoid arthritis from the ethyl acetate extracts of the roots of Lasianthus acuminatissimus Merr. MethodsVarious chromatographic techniques were used to separate and purify the constituents. Their structures were established on the basis of 1D, 2D NMR and HRMS spectroscopic analyses and their preliminary evaluation of anti-inflammation effect on the release of β-glucuronidase was carried out. ResultsEight compounds were isolated and identified as lasianthuslactone A (1), codonolactone (2), 2,5-dimethoxy-1,4-benzoquinone (3), uncargenin A (4), nonadecyl alcohol (5), 13-docosenoic acid (6), tetracosanoic acid (7) and β-sitosterol (8). Compound 3 showed a significant inhibitory effect on release of βglucuronidase rat polymorphous nuclear leukocytes activated by platelet activating factor (PAF). ConclusionCompound 1 is a new one, the others were isolated from the plant for the first time and 3 is one of active anti-inflammation compound in the plant.