Small, well-defined ground-glass nodules in the lungs may be due to benign diseases such as pneumonia and tuberculosis, which are mostly not serious; there is also a certain risk that they may be due to lung cancer, which is more serious. Lung nodules are imaging manifestations of a variety of benign and malignant lung diseases. Milled glass nodules are nodules with a milled glass component, where pure milled glass nodules have an 18% malignancy rate and mixed milled glass nodules have a 63% risk of malignancy. Small nodules are defined as pulmonary nodules <1 cm, with a malignancy rate of no more than 15%. Lung nodules with clear borders are mostly benign. Most of the clearly defined pulmonary ground-glass nodules are due to benign diseases such as pneumonia, tuberculosis, charcoal deposition, focal fibrosis, etc., which can be improved or cured by timely treatment, and most of them are not serious, and only a few patients with severe pneumonia and severe tuberculosis have serious conditions. However, there is a certain risk that the ground-glass nodules may be lung cancer. If they are lung cancer, they are more serious, and if not treated in time, they may lead to localized spread and metastasis of the lesions, which is sometimes life-threatening. However, due to the small size of the lesion, it should be an early stage of lung cancer, and timely treatment can improve the prognosis. It is recommended that the patient should consult a specialist in time and follow the doctor's advice for further examination and treatment.