Lung nodules are the imaging manifestation of various benign and malignant lung diseases, which are not serious if caused by benign diseases such as inflammation, and serious if caused by malignant tumors. Lung nodules are round-like lesions with a diameter of ≤3 cm found on chest radiographs, chest CT, etc. Lung nodules are the imaging manifestations of various lung diseases, and they can be caused by benign diseases such as pneumonia, tuberculosis, misshapen tumors, sarcoidosis, etc. or malignant tumors such as bronchopulmonary carcinoma and metastatic carcinoma of the lungs. If the nodules are caused by benign diseases such as pneumonia, tuberculosis, granuloma, etc., they are not serious. Generally, pneumonia and tuberculosis can be improved or cured by taking ceftazidime, isoniazid and other anti-infective drugs, and the prognosis of patients with severe pneumonia and tuberculosis is not good. Benign neoplastic lung diseases such as malignant tumors can be cured by surgery. If it is caused by malignant tumors such as bronchial lung cancer, the prognosis is better in the early stage by radical surgery, chemotherapy, radiotherapy, etc. Late bronchial lung cancer as well as metastatic lung cancer often affects the survival and endangers the life. It is recommended to consult a specialist for a comprehensive analysis and preliminary judgment based on the size, shape and composition of the nodule, and follow the doctor’s instructions for further examination and treatment.