131I has been used to treat hyperthyroidism for more than 60 years and is now the treatment of choice for adults in the United States and Western countries. China has been treating hyperthyroidism with 131I since 1958, and hundreds of thousands of cases have been treated so far. We have accumulated rich experience in treating refractory severe hyperthyroidism with 131I, but the frequency of use in North American countries is significantly higher than that in China and Asian countries. It is now clear that: 1. This method is safe, simple, inexpensive and highly effective, with an overall efficiency of 95%, a clinical cure rate of over 85% and a recurrence rate of less than 1%. After 3-6 months of the first 131I treatment, some patients can do the second 131I treatment if their condition requires. 2. It does not increase the incidence of thyroid cancer and leukemia and other cancers. 3. It does not affect the fertility of patients and increase the incidence of genetic defects. 4. 131I accumulates in the body mainly in the thyroid gland and does not cause acute radiation damage to organs other than the thyroid gland, such as the heart, liver and blood system, and can be used relatively safely to treat patients with severe hyperthyroidism who suffer from comorbidities of these organs. 5. Our experts are more cautious about the indications for age. In the United States and other North American countries, treatment with 131I for hyperthyroidism in patients under 20 years of age has been repeatedly reported. In the UK, children with hyperthyroidism over 10 years of age, especially those with goiter and/or poor compliance with ATD therapy, are also treated with 131I.