Abstract: The chemical constituents of the traditional medicine “Sikuaiwa”(Chloranthus multistachys Pei) were isolated and purified with medium-pressure column chromatography and preparative HPLC. These isolated chemical constituents were identified with modern spectroscopic techniques and assayed with vitro cytotoxicity. Eight pure compounds were obtained and their structures were elucidated as rosmarinic acid (1),rosmarinic acid methyl ester (2),isorinic acid (3),isorinic acid methyl ester (4),(E)-N-Phenethyl-3,4-(methylenedioxy) cinnamamide (5),caffeic acid (6),oresbiusin A (7) and 5-hydroxyuracil (8) based on detailed spectral analysis.Compounds 3—6 and 8 were isolated from the title plant for the first time.In vitro cytotoxic activity of compounds 1—8 were evaluated by using MTT method,and the results showed that compound 2,4 and 8 exhibited cytotoxic activity against HepG2 and Hep3B cell lines with IC50 values ranging from 116.8 to 150.8μmol/L.