Objective To observe the efficacy of mesenchymal stem cells (MSC) for treatment of experimental autoimmune encephalomyelitis (EAE) and the related immunoregulation mechanism. Methods EAE models of C57BL/6 mice were established with MOG_35-55/CFA emulsion and the EAE mice were randomly divided into MSC treatment group and EAE model group. MSCs were purified and cultured from the bone marrow of GFP-C57BL/6 mice. On the 15^th day of EAE model establishment, MSCs (1×10⁶/400 μL) were injected via the tail vein for the MSC treated group, and 400 μL PBS were injected for the EAE model mice. Then we recorded the clinical scores and analyzed the pathological changes of spinal cord so as to evaluate the state of EAE in each group. The peripheral blood tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), interleukin-4 (IL-4) and transforming growth factor-β (TGF-β) cytokines were evaluated by ELISA. The percent of CD4⁺Foxp3 Treg cells and GFP cells were analyzed by Flow cytometry. Results Compared with EAE model group, the MSC treated group had significantly decreased clinical score(P<0.05) and less T-cell infiltration in the spinal cord. MSC treated group had increased peripheral blood IL-4, TGF-β and decreased IFN-γ, TNF-α levels. Moreover, the MSC treated group also had greatly increased ratio of CD4 Foxp3 T cells (Treg). The MSC cells almost disappeared 10 days after transplantation. Conclusion Mesenchymal stem cell transplantation can effectively treat experimental autoimmune encephalomyelitis in mice. MSC may exert immunoregulation effect through increasing blood anti-inflammatory cytokines (IL-4, TGF-β) and decreasing proinflammatory cytokines(IFN-γ, TNF-α), which can prompt the naive cell differentiation into Treg cells. The effect of MSC remains even after disappearing for a certain time period.