Objective To study the role of Gadd45a gene in mouse hematopoietic stem cell function. Methods Sorting mouse bone marrow hematopoietic stem cells by flow cytometry ,which aim to culture monoclonal; Competitive bone marrow transplantation; The survival curves after irradiation. ResultsGadd45a gene deletion improves hematopoietic stem cell colony forming ability, but hematopoietic reconstitution capacity and survival situation after8.5Gy irradiation is no difference. Conclusion Gadd45a gene plays an important role on mouse hematopoietic stem cell function.