1, clear diagnosis, women of childbearing age to exclude pregnancy; breastfeeding women prohibited from breastfeeding for more than 4 weeks; recent myocardial infarction patients prohibited 131 iodine treatment. 2, stop taking iodine-rich food for 1 month and anti-thyroid drugs for more than 5 days, so that 131 iodine can be fully absorbed and utilized. 3.Routine physical examination and laboratory tests; determination of serum thyroid hormone levels, liver and kidney function, as well as blood, urine routine, ECG, ultrasound and other tests; if necessary, thyroid scanning imaging. Determine the thyroid absorption 131 iodine rate and effective half-life; correctly estimate the weight of the thyroid gland; to determine the dose of medication. 4, severe hyperthyroidism patients, according to the condition should first symptomatic comprehensive treatment, to avoid taking drugs induced thyroid crisis, such as anti-heart failure, anti-infection, white blood cells or give β-blockers, sedatives, etc., supplemental vitamins and potassium, magnesium and so on. Wait for the disease control in the line 131 iodine treatment. 5.Patients and their family members should understand the precautions, efficacy, possible near-term reactions and long-term complications in the treatment, and sign the informed consent form after agreeing to it. 6, before and after taking 131 iodine for 3 days, patients should rest in bed, avoid strenuous activities, avoid emotional excitement, avoid walking in public places and contacting children of young age, especially pregnant women and infants. To prevent them from receiving unnecessary radiation.