〔Abstract〕 Direct fluorescence labeling and multiparameter flow cytometry were used to detect different T lymphocyte subsets such as total T lymphocytes, helper T lymphocytes, cytotoxic T lymphocytes, regulatory T cells(Treg cells) and activated effector T cells(Teff cells) in patients with secondary myeloid leukemia retrospectively. By comparing secondary acute myeloid leukemia(S-AML), primary acute myeloid leukemia(P-AML) and healthy control group, the differences in Treg and Treg/Teff among the three groups were found to be statistically significant(P<0.05). There was an imbalance in the immune status of patients with acute myeloid leukemia. Moreover, the immune imbalance was even more pronounced in s-aml patients, which might provide new ideas for the prevention and treatment of S-AML in the future.