[Background] Coix lacryma-jobi L. is a nourishing food and a traditional Chinese medicine and has been used for the treatment of neuralgia, inflammatory diseases, and rheumatism. Little is known about the anti-tumor of Coix lacryma-jobi L.. In this study, the cytotoxic effects of Coix lacryma-jobi L. on HeLa, HepG2, and SGC-7901 were evaluated.[Methods] The cytotoxic active compounds were isolated and extraction from the stems and leaves of Coix lacryma-jobi L. The structural identification of the compound was determined using ultraviolet spectroscopy, Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The cytotoxic activity in vitro effect of the compound was determined using CCK-8, Flow cytometry, and DNA Topo I inhibition experiments.[Results] A compound F2 was isolated and purified from the petroleum ether extract of Coix lacryma-jobi L. stems and leaves. It was identified as the cycloartenol. The minimum IC50 values of HeLa, HepG2 and SGC-7901 cells for this compound were 500, 537.7, and 336.8 μg/mL, respectively. The compound had pro-apoptotic effects on three types of tumor cells, and had a significant inhibitory effect on DNA topoisomerase I.[Conclusion] This study demonstrates that cycloartenol has good cytotoxic activity in vitro, suggesting that cycloartenol could be a potential candidate as a natural antitumor drug.