131I treatment of hyperthyroidism has a history of more than 60 years, and is now the treatment of choice for adult hyperthyroidism in the United States and Western countries. China has been treating hyperthyroidism with other 131I in North America since 1958, and hundreds of thousands of cases have been treated so far. In the treatment of refractory severe hyperthyroidism with 131I has accumulated rich experience, but the frequency of use in North American countries is significantly higher than in China and Asian countries. Indications: (1) Adult Graves’ hyperthyroidism with goiter of II degree or above; (2) ATD treatment failure or allergy; (3) recurrence after surgery for hyperthyroidism; (4) hyperthyroidism heart disease or hyperthyroidism with other causes of heart disease; (5) hyperthyroidism combined with leukocytosis and/or thrombocytopenia or pancytopenia; (6) hyperthyroidism in the elderly; (7) hyperthyroidism and diabetes mellitus; (8) toxic multinodular goiter; (9) hyperthyroidism and diabetes; (10) hyperthyroidism in the elderly; (11) hyperthyroidism and diabetes; (12) hyperthyroidism and diabetes; (131I) toxic multinodular (8) toxic multinodular goiter; (9) autonomous functional thyroid nodules combined with hyperthyroidism. Relative indications: (1) Hyperthyroidism in adolescents and children, failure of treatment with ATD, refusal of surgery or contraindications to surgery; (2) Hyperthyroidism combined with functional impairment of organs such as the liver and kidneys; (3) Infiltrative synostosis: 131I can be used to treat hyperthyroidism alone in mild and stabilized moderately severe infiltrative synostosis, and prednisone may be used before and after 131I treatment in patients with progressive disease. Contraindications: Pregnant and lactating women. The main complication after 131I treatment of hyperthyroidism is hypothyroidism. The incidence of hypothyroidism has been reported to increase by 5% per year, 30% in 5 years, and 40%~70% in 10 years. In China, the incidence of early hypothyroidism is reported to be about 10%, and late hypothyroidism reaches 59.8%. Experts in nuclear medicine and endocrinology agree that hypothyroidism is an unavoidable consequence of 131I treatment for hyperthyroidism, and that the choice of 131I treatment is mainly a matter of weighing the pros and cons of the consequences of hyperthyroidism and hypothyroidism. After the occurrence of hypothyroidism, L-T4 replacement therapy can be used, which can make the patient’s thyroid function to maintain normal, the patient can have a normal life, work and study, and women of childbearing age can have a pregnancy and childbirth. Due to the high incidence of complications of hypothyroidism, patients need to be informed and sign a consent before treatment with 131I. Doctors should also inform patients of the precautions related to radiation protection after 131I treatment.