Objective:To analysis the cell morphological characteristics in chronic myelomonocytic leukemia (CMML),and investigate the expression of immune marker in the diagnose and clinical application value of CMML. Methods:Using the bone marrow biospy pathology to analysis the pathology characteristics in 39 cases of CMML. By using the immunohistochemistry to detect the expression of antibodies which included CD15,MPO,CD34,CD14,CD56,CD68 (PG-M1)and CD163 in CMML,comparison with chronic myelocytic leukemia (CML) and the acute monocytic leukemia (AMoL) patients. Results:Hypercellularity was the markedly feature of the bone marrow histology in 33 cases (84.6%)of CMML. Increased granulocytic proliferation and obviously morphological abnormalities were observed in these cases. Monocytic cells were increased in 29 cases (74.4%)and 20 cases(51.3%)presented megakaryocytic morphological abnormalities. The marker in the granulocytic lineage expresses CD15 and MPO,which had respectively positive percentage of 21.69 ± 7.06% and 33.96 ± 5.94%,there were significantly statistical differences compared with CML and AMoL. The marker in the monocytes expresses CD14-CD56-CD68(PG-M1)and CD163,which were positive (10.10 ± 2.51)%-(8.69 ± 2.66)%-(13.35 ± 4.32)%-(11.43 ± 4.15)%,respectively. Except from CD56 positive CMML and AMoL,the rest had significantly statistical differences. The original marker which was positive expressed in CMML such as CD34 had the percentage of (4.31 ± 1.98)%,which had significantly statistical differences with CML. Conclusion:Morphological and immunohistochemical features of bone marrow biopsy are helpful in the diagnosis and differentiation.