Objective It is to study the method and clinical significance of acute leukemia immunophenotyping by multi-parameter flow cytometry.Methods Immunophenotyping analysis was done by three color flow cytometry with the method of CD_(45)/SSC double parameter and scatter spot picture.Results In the 79 cases of leukemia,42 cases expressed medullary system antigen in which CD_(33) expression was the highest,12 cases(28%) with CD7 expression,2 cases(5%) with CD_2 expression,2 cases(5%) with CD_3 expression,2 cases(5%) with CD_(19) expression.39 cases expressed lymphocyte system antigen in which CD_(10) expression was the highest,6 cases(6%) with CD_(33) expression,4?cases(10%) with CD_(64) expression,2 cases was double expression leukemia.Conclusion Multi-parameter flow cytometry can accurately type acute leukemia,so it has an important value for the treatment choice and prognosis diagnosis of the patients with leukemia.