A thyroid nodule is a diffuse or nodular enlargement of the thyroid gland that is not accompanied by changes in thyroid function (hyperthyroidism or hypothyroidism) and is not due to a tumor or inflammation. A diffuse goiter will eventually develop into a nodule and become a nodular goiter. Goiter is most common in women, with a male to female ratio of 1:4, and the prevalence peaks before menopause. The incidence of single or multiple thyroid nodules and the rate of positive detection of antithyroid antibodies increases gradually with age compared to diffuse goiter. In order to increase the synthesis of thyroid hormones to restore the normal rate of thyroid hormone secretion, the body’s self-regulatory system stimulates the proliferation of thyroid epithelial cells. Ageing and the gradual decline of the body’s functions also contribute to the proliferation of thyroid epithelial cells. It has been suggested that “simple goiter and goiter with hypothyroidism are only different in degree and may have the same cause”, and that the goiter may shrink after thyroid hormone supplementation. 2, thyroid growth immunoglobulin Some reports suggest that autoimmune mechanisms may be involved in the development of goiter. 3. Role of genetic factors: Genetic susceptibility plays a role in the development of certain simple goiters. 4. Cytokines and growth factors also promote or mediate the formation of non-toxic goiter. The current significant increase in the incidence of goiter and thyroid nodules in China may be correlated with the current popularity of ultrasonography, increased resolution of ultrasonography equipment and salt iodization. Professor Teng Weiping from the Institute of Endocrinology, China Medical University summarized the important events in the history of iodine deficiency disease control in China, reviewed the salt iodization policy and the changes in the population mean median urinary iodine (MUI), and described the effects of different iodine intakes on the spectrum of thyroid diseases, the epidemiological evidence and experimental findings on the increased incidence of hypothyroidism and autoimmune thyroiditis due to excess iodine.