Thyroid disease is one of the most common and frequently-occurring endocrinological diseases. About 30% of young and middle-aged people and 50% of elderly suffer from this disease. Generally speaking, the influencing factors for the increasing incidence of the disease include self-susceptibility (as inherited disease), immune-dysfunction (autoimmune thyroid disorders), aging and gender (female). Changes in thyroid function and morphology are the major pathological changes in thyroid disease. However, only 50% of all the patients need treatments. In past 30 years when edible iodine supplementation is used to prevent goiter, much evidence indicated the role of edible iodine in the occurrence and development of thyroid disease. Insufficient or excessive intake of edible iodine both may lead to increased onset of thyroid disease. Therefore, it is of vital importance to implement and do more research on iodine supplementation at appropriate doses.