The distinction between benign and malignant thyroid tumors relies on medical history, physical examination, radionuclide scan, Doppler ultrasound and puncture cytology. Medical history: ① About 50% of thyroid nodules presenting in children are malignant. ②Single nodules occurring in young men should also be alerted to the possibility of malignancy. If a nodule occurs suddenly in a patient and develops rapidly in a short period of time, it is more likely to be malignant. Physical examination: ① A single nodule in the thyroid has a higher probability of malignancy than multiple nodules. ②Benign adenoma features: smooth surface on palpation, soft texture, and high mobility when swallowed. Malignant nodules are often accompanied by enlarged lymph nodes in the neck, and sometimes the cancer is small while there are already enlarged lymph nodes in the neck. Nuclear scan: Radioactive iodine 131 scan is applied to compare the radioactive density of the nodule with the surrounding normal thyroid tissue. Warm nodules: Mostly benign tumors, less likely to be thyroid cancer. Hot nodules: almost all are benign. Cold nodules: All thyroid cancers are cold nodules, whose margins are usually fainter, but cold nodules are not always a sign of cancer. Benign nodular goiters often have degenerative changes within the nodules due to poor circulation and may also present as cold nodules, although their margins are usually clearly visible. Color ultrasound examination: Not only can it identify whether the goiter is cystic or substantial, but it can also observe the blood flow in the mass, and those with abundant blood flow may have malignant changes. Puncture cytology: It can further clarify the nature of thyroid nodules, with a diagnostic normal rate of more than 80%. Patients who find thyroid nodules are advised to seek medical attention in a timely manner and choose between regular review, medication, surgery or microwave therapy depending on the situation.