Myelodysplastic syndrome (MDS) is a group of malignant clone diseases owing to hematopoietic stem cell abnormality, which can transform to acute myeloblastic leukemia (AML). After MDS transforms to AML, the leukemia cells usually can not be effectively killed or inhibited, and bone marrow suppression becomes fairly severe. After chemotherapy, hemorrhage and infection in the period of bone marrow suppression are usually the main reasons for mortality. Therefore, the AML patients secondary to MDS usually have poor prognosis and are difficult to treat. Recently, we utilized decitabine and regimen of cytarabine, aclacinomycin and granulocyte-colony stimulating factor (CAG) combined with haploidentical lymphocyte infusion to treat a 62-year-old male with MDS-transformed AML. The symptoms were successfully remitted, with markedly shortened bone marrow suppression and favorable outcome.