This study was purposed to investigate the conditions for improving human-mouse xenograft and the erythroid differentiation of human hematopoietic stem cells (HSC) in the xenotransplant model. The engraftments of different mouse strains (NOD/SCID or NOD/SCID/IL2rγ(null)), schemes of irradiation (single-time or 2-times radiation; Co(60)γ-ray or X-ray) and strategies of CB CD34(+) cells ex vivo culture time and lentivirus infection were compared. The results showed that at 4 weeks after transplantation, the ratio of hCD45 positive cells in bone marrow of NOD/SCID/IL2rγ(null) mice increased to (51.4 ± 13.9)%, and erythroid precursor could be detected. All of the mice receiving X-ray irradiation for 2 times (a dose of 1 Gy, then the second of 1.5 Gy, with an interval of 15 min) survived. Fresh isolated CB CD34(+) cells were cultured and infected with lentivirus for 72 h and then transplanted into receptor mouse. After 4 weeks, higher engraftment [hCD45 (51.4 ± 13.9)%] and better erythroid development [hCD71(+) GPA(+) (5.98 ± 3.46)%] were observed. It is concluded that NOD/SCID/IL2rγ(null) mice receiving X-ray irradiation for 2 times and were injected with fresh isolated CB CD34(+) cells cultured and infected with lentivirus ex vivo within 72 h show a better xenograft and erythroid development.