Thyroid nodules are classified into 0-6 categories, as follows: 1. Category 0: need to combine with other tests for a comprehensive diagnosis; 2. Category 1: normal thyroid tissue; 3. Category 2: benign lesions; 4. Category 3: less than 5% chance of malignancy; 5. Category 4: 5%-85% chance of malignancy; 6. Category 5: more than 85% chance of malignancy, requiring puncture biopsy to further clarify the nature of the nodule; 7. Category 6: malignant tumor diagnosed by puncture or cytology.