Objective To observe the effects of CD4+CD25+ regulatory T (Treg) cells induced by adoptive transfer of transforming growth factor-β (TGF-β) on the rate of embryo loss of mice of the spontaneous abortion model. Methods CD4+CD25- cells were isolated from the spleen of normal pregnant CBA/J mice and induced to CD4+CD25+ Treg cells by TGF-β in vitro. The inhibit effect of TGF-β induced Treg cells on the proliferation of self-reactive T cells was measured by the flow cytometry. The CBA/J mice were randomly divided into the normal pregnancy group and spontaneous abortion group. The latter was further divided into the blank group (spontaneous abortion model without intervention), innate CD4+CD25+T cells group (spontaneous abortion model with adoptive transfer of innate CD4+CD25+ Treg cells), TGF-β induced CD4+CD25+ T cells group (spontaneous abortion model with adoptive transfer of CD4+CD25+ Treg cells induced by TGF-β), and control group (spontaneous abortion model with injection of CD4+CD25－ T cells) according to the intervention method. On day 14 of pregnancy, the mice were sacrificed and the blood samples were gathered. The levels of serum IL-10, TGF-β1, and IFN-γ were measured by the ELISA. The expressions of Foxp3 mRNA and protein in deciduas tissues were measured by the Western blotting and Realtime PCR. The rate of embryo loss of each group was calculated. Results Compared to the blank group and control group, the levels of serum IL-10 and TGF-β1 of the innate CD4+CD25+T cells group and TGF-β induced CD4+CD25+T cells group increased; the level of serum IFN-γ decreased; the expressions of Foxp3 mRNA and protein in deciduas tissues increased; and the rate of embryo loss significantly decreased (P<0.05). Conclusion CD4+CD25+ Treg cells induced by adoptive transfer of TGF-β for mice of the spontaneous abortion model can induce Th1 and Th2 immune responses towards Th2 and decrease the rate of embryo loss.