A series of harms or disorders caused by iodine deficiency in the organism are collectively referred to as iodine deficiency disorders (IDD), which can manifest as clinical, subclinical, or insidious impairments. Iodine, as a trace element, is an indispensable nutrient for the organism; therefore, the essence of iodine deficiency disorders is a nutrient deficiency. The main sources of iodine intake in the human body are food and drinking water, and iodine deficiency in the organism is related to the iodine deficiency in the natural environment in which human beings live, i.e., the distribution of the disease is obviously endemic, and it is one of the key endemic diseases in China. Iodine is the basic raw material necessary for the synthesis of thyroid hormones, and iodine deficiency disease is actually a pathological disorder caused by insufficient synthesis of thyroid hormones, so it also belongs to endocrine diseases. Since iodine deficiency exists to varying degrees in the vast majority of regions in China, iodine deficiency disease has attracted great attention and concern from governments at all levels, and has been categorized as one of the public health problems.