The detection rate of thyroid nodules has increased significantly due to advances in diagnostic techniques. According to foreign reports, the incidence of thyroid nodules in the general population is about 30%, and about one tenth of them are malignant nodules, while thyroid cancer has become the most common head and neck surgical malignancy in the United States and accounts for about 1% of all cancers. So, let’s get familiar with this strange little organ. The thyroid gland is located in the front and center of the neck, below the familiar laryngeal nodes. The thyroid gland is like a butterfly, with left and right wings (left and right lobes) and a central body (isthmus), whose main role is to secrete thyroxine and mediate body functions. People who secrete too much thyroxine are often referred to as hyperthyroidism, which is characterized by irritability, lethargy, palpitations and hand tremors. If you don’t have enough thyroxine, you have hypothyroidism. The main character of the recent Korean drama “Oh, My Venus” has changed from Daegu Venus to a fat girl lawyer, and no matter how much she controls her diet and increases her exercise, her fat remains stubborn because of this disease. So, the thyroid gland is like the engine in our body, if it is not functioning well, the consequences are unimaginable. In addition to functional disorders such as hyper- and hypothyroidism, thyroid nodular lesions are also very common in clinical practice. Most thyroid nodules are benign nodules, while a few are malignant nodules, also known as thyroid cancer. Patients with thyroid cancer usually heal well if treated early, therefore, it is especially important to choose the appropriate screening method for early thyroid cancer. High-frequency ultrasound is usually the preferred and effective screening tool. Thyroid cancer lesions are mostly shown as hypoechoic nodules with blurred borders in 2D gray-scale ultrasound images, some of which have tiny calcifications, and some of which have a longitudinal to transverse ratio greater than 1, as if they are standing up in an oval shape. At a certain stage of disease progression, metastatic cervical lymph node enlargement can also be observed, and in color Doppler ultrasound images, blood flow signals can be observed. In recent years, there are some new ultrasound techniques applied to the diagnosis of malignant thyroid nodules, such as elastography. Simply put, elastography is the use of ultrasound instead of the physician’s hand to palpate lesions deep in the body, showing the softness or hardness of the lesions by different colors, generally, malignant lesions are harder. In addition to flexible ultrasound, we can also use ultrasonography to visualize the microvascular pattern of thyroid nodules. For some suspicious nodules, the cellular tissue of the nodules can be obtained by ultrasound-guided fine needle aspiration and observed under microscope to clarify the benignity or malignancy. Although early thyroid cancer is silent, early detection of thyroid nodules can be achieved through regular ultrasound examinations. Nodules suspected to be malignant by routine 2D and color Doppler ultrasonography can be further combined with flexible ultrasound, ultrasonography, and ultrasound-guided fine-needle aspiration cytology to identify benign and malignant and clarify whether surgery is necessary.