Thyroid nodules are very common. The prevalence of thyroid nodules in the general population is 3% to 7% on palpation, while the prevalence of thyroid nodules on high definition ultrasonography is 20% to 70%. Most thyroid nodules are benign, and malignant nodules account for only about 5% of thyroid nodules. The key to the diagnosis and treatment of thyroid nodules is to identify benign and malignant. Depending on the cause of the nodule, it can be classified as: nodular goiter, inflammatory nodule, toxic nodular goiter, thyroid cyst and thyroid tumor. The vast majority of patients with thyroid nodules have no clinical symptoms and are often detected by physical examination or by their own touch or imaging. When the nodules compress the surrounding tissues, corresponding clinical manifestations such as hoarseness, breath-holding, and difficulty swallowing may occur. Thyroid nodules are often found during ultrasound examination of the thyroid gland. The diagnosis and treatment of thyroid nodules are mostly based on ultrasound and puncture biopsy results. Only pathological examination of thyroid nodules can be performed for final characterization, and other means of examination can only be used as auxiliary tests. Ultrasound-guided fine-needle aspiration biopsy is less invasive, more precise, and has a high confirmation rate, making it a safe and efficient diagnostic modality that can reduce unnecessary surgery. Fine needle aspiration biopsy of thyroid nodules is recommended as the preferred diagnostic method for patients with clinically normal thyroid function. Ultrasound-guided biopsy can be considered for all thyroid nodules >1 cm in diameter. Thyroid nodules <1 cm in diameter are not recommended for routine performance. However, ultrasound-guided aspiration biopsy may be considered if the following conditions exist: 1. ultrasound suggests malignant nodules (hypoechoic, irregular border, microcalcifications, disturbance of blood flow signal in the nodule); 2. abnormal ultrasound images of cervical lymph nodes; 3. history of cervical radiation exposure or radiation contamination exposure during childhood; 4. history of thyroid cancer or family history; 5. positive 18F-FDGPET image Positive 18F-FDGPET 6. Abnormally elevated serum calcitonin level.