After oral administration of 131I to patients with hyperthyroidism, it usually takes 2 to 3 weeks for the gradual onset of efficacy, with symptomatic relief, shrinkage of the thyroid gland, and an increase in body weight. Subsequently, the symptoms gradually disappear and the thyroid gland shrinks significantly. In a few cases, the effect of 131I treatment can last for more than half a year. 131I treatment is also divided into courses, a course of oral 131I once, hyperthyroidism has not been cured, depending on the circumstances of the second course of treatment can be carried out in 3-6 months. Usually, the cure rate of one course of treatment is 52.6%~77.0%, the effective rate is more than 95%, the ineffective rate is 2%~4%, and the recurrence rate is 1%~4%. Generally, 131I is more effective for GD hyperthyroidism, and the cure rate of two courses of treatment is higher, up to 95% or more. For patients with nodular goiter or oversized and hard thyroid gland, several courses of treatment are often needed to cure.