Apart from endemic goiter and endemic cretinism, which are two typical manifestations of iodine deficiency, the greatest danger of iodine deficiency to human health is intellectual disability. Therefore, it is listed as one of the three major micronutrient malnutrition diseases with vitamin A deficiency and iron-deficiency anemia, which are the focus of prevention and elimination by international organizations such as WHO and UNICEF. The government of China attaches great importance to the elimination of iodine deficiency disorders, and has implemented comprehensive prevention and treatment measures nationwide since 1995, mainly salt iodization, which has significantly improved the iodine nutrition status of residents and achieved the goal of eliminating iodine deficiency disorders at the national level. With the rapid development of China’s economy and society, people’s living standards and dietary nutrition have changed significantly, and the question of whether iodized salt can cause iodine overdose has become a common concern. This topic adopts a question-and-answer format, highlighting key and hot issues, and strives to be concise, easy to understand, and convenient to grasp the key knowledge of iodine deficiency disease prevention and treatment.