In this experiment we observed the direct effect of β-elemene,OL.Curcuma aromatica and Tween 80 on L615 leukemic cells in vitro.The results showed that all of them were cytotoxic to L615 leukemic cells,LD50 of β-elemene was 2.57 μg/ml,that of OL.curcuma aromatica was 31.2 μg/ml,that of Tween 80 was 291.3μg/ml.After β-elemene treatment L615 leukemic cells changed morphologically,including degeneration and death,their ability to cause leukemia was decreased.