Objective:To prepare a new type of anti-leukemia immunotoxin with killing activity.Methods:The method of cytotoxicity was used to study the activity of the immunotoxin after the induction of IPTG. Results:The expressed fusion proteins were detected mostly as inclusion bodies at high level.The result showed IL3-PE38KDEL had liable activity of toxicity. Conclusion:The fusion protein IL3-PE38KDEL has good biological activity

which paves way for the further study on its treatment of leukemia.