Abstract: Objective To investigate the effect of combined transplantation of human umbilical cord derived mesenchymal stem cells（hUC-MSCs）and hematopoietic stem cells on acute myloid leukemia. Methods The patient with acute myloid leukemia received marrow and peripheral blood stem cell transplantation（UD-PBSCT）with granulocyte clony-stimulating factor（G-CSF）.hUC-MSCs were isolated,culture-expanded from human umbilical cord after enzyme digestion,and cotransplantation to patient with haplo-hematopoietic stem cells.The donor of haplo-hematopoietic stem cells was her elder-brother.Graft-versus-host disease（GVHD）was prevented with CsA,MTX,ATG,CD25 and mycophenolate mofetial. Results The number of MNCs and CD34+ cells was 7.92×10⁸/kg and 4.1×10⁶/kg,respectively in the donor.The number of neutrophils and platelets was over 0.5×10⁹/L and 20×10⁹/L on days 14 and 15,respectively.On day 24,the chimeras accounted for 100%.Grade 1 aGVHD was observed on about day 40,and no other severe complications occurred after treatment. Conclusion Transplantation of combined haplo-hematopoietic stem cells and hUC-MSCs is safe and simple,and can promote the function recovery of hematopoietic cells.