After thyroid cancer surgery, all patients should receive endocrine therapy, i.e. oral thyroxine tablets, except for some children who need to receive I131 therapy. The thyroid gland is vital to the body’s metabolism. After total removal, thyroxine tablets are required. This is for two purposes. First, thyroxine is needed for human metabolism and must be supplemented in vitro to meet the body’s physiological needs, especially for children, where thyroxine deficiency can have an incalculable negative impact on growth and intellectual development;? Secondly, thyroxine tablets can inhibit the secretion of TSH, thus inhibiting the recurrence and metastasis of thyroid cancer, which is known as endocrine therapy. The mechanism is that most differentiated thyroid cancers are TSH-dependent tumors and their growth is stimulated by TSH, so inhibiting TSH secretion can achieve the purpose of inhibiting the growth and metastasis of thyroid cancer tumors. Too little will lead to hypothyroidism, which will adversely affect the growth and development of the child, while too much will lead to hyperthyroidism. When taking thyroxine tablets after thyroid cancer surgery, the dose is usually high and the TSH should be controlled to less than 0.1 mU/L. It would be better if it can be controlled to less than 0.01 mU/L, but care should be taken to prevent hyperthyroidism. Therefore, after thyroid cancer surgery, children should have their thyroid function checked regularly and the oral dose of thyroxine tablets should be adjusted according to TSH, T3 and T4 levels, usually at least once every six months.