Myasthenia gravis (MG) is an autoimmune disease with impaired neuromuscular junction transmission. The main manifestations are easy fatigue of skeletal muscles, aggravation of symptoms after activity and reduction after rest, and improvement of symptoms after taking bromipyridostigmine. The prevalence rate is about 1-2/10,000. Clinical manifestations: involvement of extra-ocular muscles manifests as droopy eyelids and double vision; involvement of extremities manifests as weakness of extremities and difficulty in going up stairs; involvement of throat muscles manifests as difficulty in swallowing, weakness in chewing, slow eating and sputum; involvement of respiratory muscles manifests as chest tightness and difficulty in breathing. MGFA clinical typing: Type I: Ocular muscle alone Type II: Mild involvement of muscles other than the extraocular muscles, may be accompanied by ocular muscle involvement IIa. Mild involvement of muscles of the extremities or trunk IIb. Mild involvement of respiratory muscles of the pharynx Type III: Moderate involvement of muscles other than the extraocular muscles IIIa. Moderate involvement of muscles of the extremities or trunk IIIb. Severe involvement of muscles other than extraocular muscles IVa. Severe involvement of extremity or trunk muscles IVb. Severe pharyngeal respiratory muscle involvement Type V: Tracheal intubation with or without ventilator