Physical growth retardation and dysplasia are characteristic of endemic cretinism. Patients are short and disproportionate, with the lower part of the body shorter than the upper part, and skeletal development is delayed, manifested by late appearance of the bone nucleus and small development. Endemic cretinism is a preventable disease, but the key is early detection. The effect of thyroxine on brain function varies at different ages. If prevented within 1 year of age or earlier in affected children, the prevalence is greatly reduced. If not diagnosed and treated early, the effects on mental development and morphology are permanent. Endemic cretinism can occur in fetal iodine deficiency or inadequate correction of iodine deficiency, with iodine intake less than 20 micrograms per day. If mild iodine deficiency or inadequate correction of iodine is not sufficient to cause cretinism, subcretinism may occur. For this reason, women of childbearing age in the disease area should be advocated to take iodine oil by injection or orally, while micro cord blood T3, T4 and TSH tests should be performed on newborns for early detection, diagnosis and treatment. Salt iodization is a simple and effective measure to prevent and treat iodine deficiency disorders. Salt iodization ratio of 1:50,000 can effectively prevent diarrhea; 1:20,000 can prevent diarrhea. The potassium iodide added to salt is prone to oxidation and sublimation, and since 1993 it has been replaced by potassium iodate, which is more stable. In the process of packaging, storage, transportation and consumption of iodized salt, care must be taken to keep it dry, tightly packed and impermeable, protected from the sun, and stored in a dark place. It has been determined that the iodine loss rate in iodized salt after six months of storage in different ways is: 10% in the tank; 29.4% in the sack; 57.8% in the drawer; 1.9% in boiling for 2h; 66.1% in baking for 2h.