The trace element selenium has an important biological significance for human beings and is an essential trace element in the human body, and the thyroid gland contains the highest amount of selenium among human organs. The main form of selenium in the body to play a function in the selenocysteine as the active center of the protein, called selenoprotein. Twenty-five selenoproteins have been identified from the human body, and there are six main groups: glutathione peroxidase family, iodothyronine deiodinase family, selenoprotein P, selenoprotein W, thioredoxin reductase and selenosubstituted phosphate synthase. Selenium plays a variety of biological roles in the body, such as antioxidant, immune function enhancement and antitumor. Selenium is involved in the synthesis, activation and metabolic processes of thyroid hormones, and plays an important subterfuge in the thyroid disturbance oxidation system and immune system. Selenium deficiency is closely related to goiter, autoimmune thyroid disease, low T3 syndrome, thyroid cancer and other diseases. Administration of selenium-containing preparations to patients with certain thyroid disorders can improve thyroid function, which provides an alternative approach to the treatment of thyroid disorders.