Ryanodine receptor （RyR） is an important calcium channel in the endoplasmic reticulum/sarcoplasmic reticulum and plays an important role in the excitation-contraction coupling mechanism of skeletal muscle. Patients with myasthenia gravis （MG） and positive RyR antibody often have thymoma and are not sensitive to conventional treatment， which may delay early identification and treatment in clinical practice. The serum level of RyR antibody is significantly associated with the severity of clinical symptoms. This article discusses the clinical features and treatment process of four MG patients with positive RyR antibody， so as to improve the awareness and diagnosis and treatment levels of this disease.