Type 1 diabetes (T1D) results from the host immune disorder, which elicits the selective destruction of insulin-producing s in the pancreatic islets. Bone marrow transplantation (BMT) has been reported to treat T1D in numerous studies, and has been proved to be effective in treating T1D based on immune ablation and regeneration. In this study, we aimed to evaluate the curative effect of syngeneic bone marrow transplantation (syn-BMT) and to analyze peripheral blood lymphocyte phenotypes of streptozotocin (STZ)-induced diabetic mice after syn-BMT, and further to reveal possible mechanisms of syn-BMT involved in normalization of blood glucose. After multiple injections of low-dose STZ, most male C57BL/6J inbred mice got hyperglycemia, and then underwent syn-BMT. Fasting blood glucose was detected every 10 days after syn-BMT. The hemocytes count was evaluated every 3 days after syn-BMT in mice. Before syn-BMT, and on days 30, 60, and 90 after syn-BMT, we examined proportion of peripheral blood T lymphocytes, CD19(+) B lymphocytes, and NK cells by flow cytometry. Our data showed that hyperglycemia could be reversed and normal blood glucose level could be maintained in the whole observation period after syn-BMT. The peripheral blood elevated CD4(+)/CD8(+) T lymphocyte ratio, CD19(+) B lymphocyte proportion and NK cell proportion in diabetic mice significantly decreased after syn-BMT. This study indicated that syn-BMT could reverse hyperglycemia and revealed immune ablation and immune system regeneration might be a possible mechanism of syn-BMT involved in normalization of blood glucose.