Abstract: Objective To research clinical effect of statins combined with mesenchymal stem cell infusion in treatment of autoimmune myasthenia gravis. Methods A total of 20 consecutivecasesof autoimmune myasthenia gravisbetween February,2013 and May,2014 were divided randomly into control group and experiment group with 10 cases in each group.The patients in the control group received conventional hormone and(or) immunosuppressive therapy,while the patients in the experiment group received statins combined with mesenchymal stem cell infusion.Lennon score of muscle strength,comprehensive function score of clinical symptoms including progress degree,cognitive function,motor function,self-care action and social adaptation,and CD28 expression of CD4⁺T lymphocyte cell and IL-4 level were compared between the two group. Results After about three months of follow-up, two groups of patients Lennon scores were lower, comprehensive function scores were increased, and the more obvious changes in the observation group,groups were significantly more when compared with those the control group(P<0.05).And the progress degree,cognitive function,motor function,self-care action and social adaptation scores in the experiment group were all better as compared with the control group(P<0.05).CD28 expression and IL-4 levels after the treatment were lower in both groups,especially in the experiment group(P<0.05). Conclusion The statins combined with mesenchymal stem cell infusion can greatly improve the clinical symptoms of patients with autoimmune myasthenia gravis by decreasing CD28 expression and IL-4 levels.