Iodine, as a trace element, is an indispensable nutrient for the body. Iodine is a raw material necessary for the synthesis of thyroid hormones, and iodine deficiency can cause a series of pathological changes in the human body, called iodine deficiency disorders, which are often regional and can also be disseminated. Iodine deficiency, endemic goiter and endemic cretinism (congenital hypothyroidism, dementia, developmental disorders) have been studied for thousands of years, and in ancient China, seaweed and kombucha were used to treat goiter. In the 1930s, Chinese scholars have conducted iodine deficiency studies and tried salt iodization to prevent and treat endemic goiter and cretinism. Feng Zhihai, Department of Endocrinology, The First Affiliated Hospital of Henan College of Traditional Chinese Medicine China has made a lot of efforts to implement the declaration of the 1990 World Conference on Children, which called for the elimination of iodine deficiency disorders in the world, and has promoted salt iodization nationwide to basically control iodine deficiency disorders and endemic cretinism. In recent years. Both at home and abroad have reported an increase in the incidence of hyperthyroidism after salt iodization. At present, this issue is still under in-depth discussion, because in addition to salt iodization, other environmental factors are not yet fully understood.