Abstract: Five compounds were isolated from an ethanol extract of Artemisia deversa Diels by solvent extraction, Diaion HP-20, CHP20/P120 MCI, Sephadex LH-20, silica gel and preparative high performance liquid chromatography. Their structures were elucidated by MS, NMR and X-ray as artemideversal (1), 7-hydroxy-6-methoxycoumarin (2), 6,7-dimethoxycoumarin (3), caffeic acid (4) and 4',5,7-trihydroxy flavone (5). Compound 1 is a new eudesmane-type sesquiterpene. In vitro cytotoxic activities of the five compounds were explored by MTT testing with HepG2, A549, HeLa and MRC-5 cell lines. Results show that compounds 1 and 5 significantly inhibited cellular proliferation. The IC₅₀ of compound 1 in A549 and HepG2 cells was 8.36 and 16.51 μmol·L^-1; the IC₅₀ of compound 5 in A549 and HepG2 cells was 17.06 and 7.95 μmol·L^-1.