Abstract: Objective To research the effect of Chinese medicine “dong xia wan” on 6 human tumor cell lines in vitro. Methods growth and cell cycle of human tumor cells lines were determined by microplate staining and flow cytometry measurement. Results growth of all examined tumor cell lines were markedly inhibited by “dong xia wan”.The inhibitory rate of growth was increased as the concentration of drug was increased.IC50 of the drug was like for most tumor cell lines.For nasopharyngeal carcinoma (NPC) cells treated by the drug,the percentage of G2 was much increased and cell apoptosis was induced. Conclusion Chinese medicine “dong xia xan” can inhibit the growth of NPC and many kinds of tumor cells.