This study was purposed to explore the effectiveness of mixed transplantation of HLA mismatched bone marrow hematopoietic stem cells(HSC), peripheral blood HSC and umbilical cord blood HSC for treatment of pediatric blood diseases. From August 2012 to December 2012, five children with refractory hematological diseases in our hospital received allogeneic hematopoietic stem cell transplantation. The mixed grafts consisting of HLA-mismatched bone marrow HSC, peripheral blood HSC and umbilical cord blood HSC were used to observe the effects of umbilical cord blood HSC on the time of hematopoietic reconstruction of bone marrow, STR chimeric degrees, incidence of GVHD. and early transplant-associated complications. The results showed that all 5 children patients were grafted successfully with the median grafted time of 11 d for ANC>0.5×10(9)/L and 10 d for Plt>20×10(9)/L, respectively. On day 30, the STR-PCR test of peripheral blood showed a stable complete chimera. Five cases suffered from mild to moderate symptoms of GVHD, showing with I-II grade of skin GVHD and in which two cases suffered from diarrhea, showing I-II grade of intestinal GVHD. All the 5 patients had no liver function damage. One patient died of severe hemorrhagic cystitis and multi-site infection, and the remaining four cases survived so far on the current median follow-up time of 137 d (130 d-250 d). It is concluded that transplantation of the mixed HLA mismatched bone marrow HSC, peripheral blood HSC, with third-party cord blood HSC can increase the survival rate for pediatric patients with blood disease.