Iodine-131 has been used to treat hyperthyroidism for more than 60 years, and is now the treatment of choice for adult hyperthyroidism in the United States and western countries. In China, hundreds of thousands of cases of hyperthyroidism have been treated with Iodine-131 since 1958, and rich experience has been accumulated in the treatment of refractory severe hyperthyroidism with Iodine-131, but the frequency of its use in Europe and the United States is significantly higher than that in our country and Asian countries. It is now clear that this method is safe, simple, inexpensive and highly effective, with a total effective rate of 95%, a clinical cure rate of more than 85% and a relapse rate of less than 1%. 3~6 months after the first iodine-131 treatment, some patients can have the second iodine-131 treatment if their condition requires. Iodine-131 mainly accumulates in the thyroid gland, and does not cause acute radiation damage to organs other than the thyroid gland, such as the heart, liver, blood system, etc., so it can be more safely used to treat severe hyperthyroidism patients suffering from complications of these organs. Our experts are more cautious about the age indication. In the United States and other North American countries, the use of treatment for hyperthyroidism in patients under 20 years of age has been repeatedly reported. In the United Kingdom, Iodine-131 is also used for treatment of hyperthyroidism in children over 10 years of age, especially those with goiter and/or poor compliance with ATD treatment. In 2004, the Nuclear Medicine Branch of the Chinese Medical Association formulated the indications, relative indications and contraindications for the treatment of hyperthyroidism with iodine-131 in China, which are supplemented and refined in this guideline. Indications: adult Graves’ hyperthyroidism with goiter of degree II or above; ATD treatment failure or allergy; recurrence after surgery for hyperthyroidism; hyperthyroidism heart disease or hyperthyroidism with other causes of heart disease; hyperthyroidism combined with leukopenia and/or thrombocytopenia or pancytopenia; hyperthyroidism in the elderly; hyperthyroidism and diabetes mellitus; toxic multinodular goiter; autonomic functional thyroid nodules combined with hyperthyroidism. Relative indications: hyperthyroidism in adolescents and children, failure of treatment with ATD, refusal of surgery or contraindications to surgery; hyperthyroidism combined with liver, kidney and other organ function damage; infiltrative proptosis. Iodine-131 can be used alone to treat hyperthyroidism in mild and stable moderate or severe invasive proptosis, and prednisone can be added before and after iodine-131 treatment for patients with progressive stage. Contraindications: Pregnant and lactating women. The main complication of iodine-131 treatment for hyperthyroidism is hypothyroidism. Foreign countries report that the incidence of hypothyroidism increases by 5% per year, reaches 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 iodine-131 treatment of hyperthyroidism, and that the choice of iodine-131 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 maintain normal, and the patient can live, work and study normally, and women of childbearing age can be pregnant and give birth.