Abstract: Objective To observe the effect of E838 combination with the chemotherapy drug Cyclophosphamide(CTX ) on tumor inhibition and life prolonging for leukemia L1210 cell mouse with tumor. Methods The model is IRM-2 mice whose tumor was induced by L1210.There were groups of control,CTX,E838,E838 and CTX, the experiment indicator were rate of tumor inhibition, number of bone marrow nucleated cells, index of spleen and thymic and rate of life prolonging, then observe the difference on these groups. Results Tumor's weight on the group of E838 was obviously lower than the group of control, the group of E838 and CTX has strong inhibition on leukemia L1210 cell of mouse with tumor, and mice in these group has a longer life. Conclusion E838 can inhibit leukemia L1210,it also can improve effect and enhance immune system when apply together with CTX.