Abstract： Objective To detect double immuno-phenotype of acute leukemia by the application of flow cytometry (FCM). Methods Four-color FCM was used to analyse 23 cases of acute leukemia of double immune phenotype. Results Among 23 cases, cCD3 was expressed in 10 cases (43.4 %), cCD79a in 16 cases (69.6 %), cMPO in 20 cases (87.0 %), TdT in 14 cases (60.9 %), CD34 in 19 cases (82.6 %) and CD117 in 20 cases (87.0 %). 13 cases (56.5 %) expressed both myeloid and B lymphocyte antigens, in which cCD79a and cMPO were positively expressed, 7 cases (30.4 %) were found to express both myeloid and T lymphocyte antigens of cCD3 and cMPO 3 cases (13.04 %) were positive for both cCD3 and cCD79a. Conclusion cCD3,cCD79a, and cMPO were lineage specific antigen markers, which could be used for diagnosis and differential double phenotype leukemias. FCM is a useful and reliable method for diagnosis of acute leukemia, and guidance of treatment and prognosis of leukemia in clinical.