The lung nodules of thyroid cancer need to be improved by thin-layer CT examination to understand the possible nature of the lung nodules. If the CT indicates that the lung nodule is benign, it can be reexamined in 0.5-1 year. If the nodule is considered malignant, it is necessary to further understand whether it is a primary lung tumor or a metastasis of thyroid cancer. If thyroid cancer has been treated surgically, such as total thyroidectomy, iodine-131 therapy can be performed to determine whether the lung nodules are related to thyroid cancer by the iodine intake of the lung nodules. If it is considered to be metastatic cancer, which originates from the thyroid gland, iodine-131 treatment can be performed. However, if the nodule is considered to be a primary lung nodule, puncture examination or surgery is required.