There is no fixed number of times that Iodine 131 should be done for total thyroidectomy, it needs to be decided according to the patient’s condition. There are two functions of iodine 131 radionuclide treatment after total thyroidectomy, one is thyroid clearance, which can remove the residual thyroid tissue as well as cancerous tissue after total thyroidectomy, so that the tumor cells can be completely removed, thus preventing recurrence. The second function of iodine 131 treatment is to clear the lesions, for some metastatic lesions that cannot be removed. Generally, iodine 131 radionuclide therapy is started 3~4 weeks after total resection. The number of iodine 131 radionuclide treatments after total thyroidectomy is not fixed, it needs to be judged according to the imaging examination combined with the patient’s condition, and generally requires 2-3 treatments. Generally, the thyroid gland and residual cancer foci can be removed in one session, but if there are metastases in the lungs, liver and other parts of the body before the operation, the number of sessions will be increased to 3-6 sessions. However, for other metastases, such as bone and lymph node metastases, 1-2 times are sufficient, as there is no point in doing more treatments. After iodine 131 treatment, patients need to pay attention to rest, prevent infection, avoid fatigue and mental stimulation, and consult the doctor in time for discomfort.