Objective To study the characteristics of child acute lymphocytic leukemia (ALL) immuno-phenotype and evaluate its diagnosis value. Methods Direct immunofluorescence staining and CD45/Side Scatter (SSC) gating of flow cytometry were used for immunophenotyping in 111 cases of child ALL. The relation of mor-phology and immunology classification was analyzed. Results Three categories could be identified,including 81 ca-ses (73.0%) of B lineage ALL, 16 cases (14.4%) of T lineage ALL and 14 cases (12.6% ) of B/T lineage ALL. There were 25 cases (22.5% ) of ALL expressing myeloid-associated antigens. According to the FAB Morphology classification,59 cases (53.2%) of L1 type and 47 cases (42.3%) of L2 type were diagnosed. The two cases (1.8%) of L3 type were classified as one case of null-ALL and one case of B-ALL. One case (0.9%)of acute my-eloblastic leukemia (AML-M2a) was identified as null-ALL. The two cases that could not be diagnosed by FAB clas-sification were c-ALL. Conclusion The immunophenotyping helps to identify the character of leukemia with an im-portant value in diagnosis of child ALL.