Thyroid nodule category 3 is an ultrasound classification, and thyroid nodules categorized as category 3 or below are more likely to be benign. The malignancy rate of category 3 thyroid nodules is <2%. If a benign nodule is diagnosed and there are no clinical symptoms, it is usually not serious and can be followed up regularly. Ultrasound is the most important imaging tool for evaluating thyroid nodules. Ultrasound can determine whether the nodule is solitary or multiple, the size of the nodule, the morphologic features of the nodule, and the blood supply of the nodule. By evaluating the morphological features of the nodule, sometimes in conjunction with its blood supply characteristics, ultrasound can help determine the risk of malignancy in thyroid nodules. It is recommended that patients who have been diagnosed with a category 3 thyroid nodule follow standardized treatment as prescribed by their physician.