Pulmonary nodules are round lesions less than 3 cm in diameter that appear in the lungs; among them, lesions greater than or equal to 1 cm in diameter are called large nodules; those less than 1 cm are called small nodules. With the advent of imaging techniques such as high-resolution CT of the chest, more and more small nodules are being detected before the clinic, how to determine whether they are benign lesions or fearful malignant tumors? Physicians can improve the diagnosis of small pulmonary nodules by combining high-resolution CT (HRCT), especially spiral CT, to magnify the local morphology of the lesion and observe its surroundings. The nature of the lesion is often determined clinically in a comprehensive manner with respect to the imaging characteristics of the small nodule and its dynamic changes, as well as the patient’s own symptoms. The guidelines for the management of small pulmonary nodules proposed by Wen Peng of the Department of Respiratory Medicine at Shandong Chest Hospital in the international Fleischner Society, which integrates multiple lines of evidence from interrogative medicine and is now widely used, are briefly described as follows: The guidelines divide the observed population into low-risk and high-risk patients. For low-risk patients: nodules less than or equal to 4 mm: no follow-up; 4-6 mm: follow-up at 12 months, stop if no change; 6-8 mm: follow-up at 6-12 months, follow-up at 18-24 months if no change; greater than 8 mm: enhanced CT, PET or puncture at 3, 9 and 24 months. For high-risk groups: nodules less than or equal to 4mm: follow up once in 12 months and stop if there is no change; 4-6mm: follow up once in 6-12 months and once in 18-24 months if there is no change; 6-8mm: follow up once in 3-6 months and once in 18-24 months if there is no change; >8mm: same as low-risk groups. 2. the incidence of lung cancer in people under 35 years of age is very low, less than 1%, and they are sensitive to radiation, follow-up needs to be cautious and should be low-dose scans; 3. patients with fever should consider the possibility of inflammation, and review after anti-infection or short-term review is recommended; 4. lung cancer of lesions located in the upper lobe is more common; 5. screening detects significantly more lethal cancer in patients who smoke than non-smokers, and the growth rate of lesions is significantly higher than non-smokers6 Nodules smaller than 4 mm are basically benign, and even for patients who smoke, the malignancy rate is less than 1%;7. Screening lesions larger than 8 mm have a 10-20% chance of malignancy and should be treated more aggressively.