Abstract: Objective To investigate the curative effect and safety of transplantation of haploidentical hematopoietic stem cells（alloHSCT） combined human umbilical cord derived mesenchymal stem cell（hUC-MSC） for severe aplastic anemia-I（SAA-I）. Methods Fourteen patients who diagnosed as SAA-I in our hospital and received haploidentical allo-HSCT from June 2012 to December 2013 were enrolled in this study. Graft came from haploidentical hematopoietic bone marrow and peripheral blood mobilized with granulocyteclony stimulating factor（G-CSF）, and the human umbilical cord derived mesenchymal stem cells（hUC-MSC） were infused as the third-party cells. Conditioning regimen consisted of rabbit anti-thymiclymphocytes protein（ATG）, cyclophosphamide（CTX） and fludarabine（Flu）, and the graft versus host disease（GVHD） was prevented with CSA, MMF, and CD25. Results All patients achieved hematopoietic reconstitution. The average time for neutrophils count＞0.5×109/L was 10.7 days, and for Plt level＞20×109/L was 13.3 days. Of the 7 patients had aGVHD, 2 were grade Ⅰ-Ⅱ and 5 were grade Ⅲ-Ⅳ. Three patients showed transplantation related mortality. Conclusion Haploidentical allo-HSCT combined with umbilical cord MSC infusion is a safe and effective treatment for refractory severe aplastic anemia-I with rapid hematopoietic recovery and few transplant complications.