Objective To investigate the early prediction and monitoring value of real time fluorescence quantitative PCR(qPCR) detection of BCR-ABL mRNA on chronic myelogenous leukemia(CML)patients with minimal residual disease(MRD)after alloge-neic hematopoietic stem cell transplantation(allo-HSCT).Methods From January 2013 to January 2016 in People's Hospital of Yantian District,School of Medicine in Shenzhen University and Shenzhen Hospital of Peking University,67 cases of outpatient and hospitalized patients with chronic myelogenous leukemia in the Department of Hematology were selected as the observation group, and 50 healthy people who took physical examination in the People's Hospital of Yantian District at the same period of time were se-lected as the control group.BCR-ABL mRNA levels before and after allogeneic hematopoietic stem cell transplantation in patients with chronic myelocytic leukemia were detected by qPCR.Results The BCR-ABL mRNA results in the control group were nega-tive.Before transplantationin the levels of BCR-ABL mRNA in patients with CML in accelerated and blastic phase were higher than that in patients in chronic phase(P<0.05);After transplantation the BCR-ABL/ABL ratio of qPCR detected at all time points in the first 36 months was significantly lower than that before the transplantation,and the difference was statistically significant(P<0.05);qPCR can still detect the level of BCR-ABL/ABL expression after 36 months of transplantation.Conclusion qPCR is accu-rate and reliable,and has important clinical application value for the clinical diagnosis of chronic myeloid leukemia and minimal re-sidual disease detection.