Allogeneic hematopoietic stem cell transplantation (allo-HSCT) appears to be an efficient tool to cure refractory anemia with excess blasts-1 (RAEB-1), refractory anemia with excess blasts-2 (RAEB-2) and acute myeloid leukemia (AML) secondary to myelodysplastic syndrome (MDS). At present, the best conditioning regimen for RAEB-1, RAEB-2 and AML secondary to MDS undergoing allo-HSCT remains in discussion. In this prospective randomized controlled study, the safety and efficacy of G-CSF+ Decitabine + BUCY and BUCY myeloablative conditioning regimens in patients with RAEB-1, REAB-2 and AML Secondary to MDS undergoing allo-HSCT are evaluated.