Objective:To observe the expression of BCR/ABL fusion gene and FoxO3a transcription factor in the patients with primary or crisis blast CML leukemia. Methods:Using EVA Green,real-time RT-PCR methods for the detection of BCR/ABL,FoxO3a and GAPDH were explored. BCR/ABL and FoxO3a gene in 25 PBMC samples with primary CML leukemia and that of 25 cases with crisis blast CML leukemia were detected by real-time RT-PCR and 30 cases of health adults were also detected for FoxO3a gene. The difference of those genes expression between the groups was analyzed by ΔΔCt relative quantity means, in which GAPDH gene was used as control. Results:The expression of BCR/ABL fusion gene in the patients with crisis blast leukemia was 4.72 times higher than that of the patients with primary CML leukemia.For the expression of FoxO3a gene,the group of health adults was 143.39 and 8.18 times higher than those of primary and crisis blast leukemia group,respectively. Conclusion:Over-expression of BCR/ABL fusion gene and low-expression of FoxO3a were possibly correlated with the pathology process of CML in different phase.