Currently, we have more than six hundred thousand immigrants in Taiwan. With the variation of environment and cross-cultural diet, it has influence on immigrant workers’ health. Thyroid gland plays an important role in endocrine system, and thyroid hormone mainly related to iodine. Daily food is the main source of iodine. Iodine deficiency disorders (IDD), including abortions, stillbirths, congenital anomalies, mental retardation, hypothyroidism, goiter and iodine-induced hyperthyroidism are caused by inadequate intake of iodine. After immigrants come to Taiwan, cross-cultural diet influence on iodine nutrition and thyroid function. This topic focuses on thyroid disorders associated with iodine nutrition, hoping this article let everyone learn more knowledge of the thyroid deficiency disorders, iodine nutrition, recommended daily allowances and iodine-induced hyperthyroidism.