Myasthenia gravis (MG) is an autoimmune disease caused by dysfunctional transmission at the nerve-muscle junction. The main clinical manifestations are partial or generalized skeletal muscle weakness and easy fatigue, with symptoms worsening after activity and decreasing after rest. The causes of the disease are divided into two categories: one is congenital heredity, which is rare and not related to autoimmunity; the second is autoimmune disease, which is the most common. The cause of the disease is still unclear, but it is generally believed to be related to infection, drugs, and environmental factors. Meanwhile, 65% to 80% of patients with myasthenia gravis have thymic hyperplasia and 10% to 20% have thymoma.