Objective To develop a mouse model of myasthenia gravis.Methods C57BL/6J mice were immunized with the mixture of acetylcholine receptor extracted from Torpedo Californica and complete Freund's adjuvant.After twice strengthened immunization,several indexes including myodynamia,electromyogram,diaphragma end-plate electron microscopy and serum anti-nAChR level were tested.Results Compared with the control,the myasthenic mice displayed myodynamia-attenuating,and the electromyogram showed an apparently declined amplitude of gastrocnemius combined action potential.The electron microscopic examination demonstrated flattened postsynaptic membrane,its folds diminished and showed vacuolar degeneration.The serum antibody level in the myasthenic mice increased significantly.Conclusion We have successfully established a mouse model of myasthenia gravis,which may be helpful in investigation of mechanisms of MG and pursue new ways to treat autoimmune diseases.