Small pulmonary nodules are a common and difficult to diagnose disease in thoracic surgery, and its diagnosis and treatment has been a difficult clinical point and hot spot for discussion. Its etiology is complex, its clinical manifestations lack specificity, and its diagnosis is difficult and easily misdiagnosed and missed. Small pulmonary nodules are various kinds of isolated hyperplastic masses in the lung found in the imaging. To determine whether small pulmonary nodules are lung cancer requires very rich clinical diagnostic experience. Then how is the diagnosis of small pulmonary nodules encountered clinically? 1.For each patient with isolated pulmonary nodules, physicians must pay high attention to determine whether it is transformed to lung cancer, and must also trace the previous chest and other imaging data; 2.For imaging showing isolated pulmonary nodules, stable for more than two years, if a recurring glassy shadow is found, a re-evaluation must be made and further examination; 3.For small nodules less than 8 mm, with calcified, clear and isolated structural pulmonary small nodules, no further examination is advocated, but high-resolution CT is required every 2 years; 4, for small pulmonary nodules in the 8-10 mm, continuous CT follow-up scans should be performed, because the malignancy rate of these types of nodules may be around 5%, and it is recommended that CT examinations should be performed at the 3rd, 6th, 12th, and 24th months, respectively, from the date of detection; 5, for small pulmonary nodules of at least 8-10 mm in diameter Patients with isolated pulmonary nodules (SPN) of variable nature, when clinical evidence and imaging findings are associated with conflicting results, such as when the clinical inference of malignancy is high and PET-CT results are negative or when benign diagnostic findings requiring treatment are suspected, and when the patient expects a definitive diagnosis before surgery, it is recommended that for peripheral lesions unless puncture is contraindicated or the site of the lesion cannot be punctured, trans Needle aspiration biopsy of the chest wall. Bronchoscopy is feasible when air bronchial signs are present (2C); 6. For surgically resectable sub-centimeter lung nodules without risk factors for lung cancer, the frequency and duration of follow-up (low-dose CT) depends on the size of the nodule: 7. Pulmonary nodules measuring less than 4 mm in diameter do not need to be followed up, but patients should be fully informed of the risks and the benefits of follow-up; 8. Pulmonary nodules with a measured nodal diameter of 4-6 mm are reassessed at 12 months without long-term follow-up unless the lesion is enlarged; 9. Lung nodules with a measured nodal diameter of 6-8 mm are followed up at 6-8 months and then again at 18-24 months unless the lesion is enlarged (2C); 10. For surgically resectable subcentimeter lung nodules with one or more risk factors for lung cancer, the frequency and duration of follow-up (low-dose CT) depends on the The size of the nodule: 11. Lung nodules measuring less than 4 mm in diameter are reassessed at 12 months without long-term follow-up unless the lesion is enlarged; 12. Lung nodules measuring 4 to 6 mm in diameter are followed up at 6 to 8 months and then again at 18 to 24 months unless the lesion is enlarged; 13. Lung nodules measuring 6 to 8 mm in diameter should be followed up at 3, 6, 9, 12, 24 months unless the lesion is enlarged (2C). Small lung nodules is a unique term in the medical field, and its mutation into lung cancer has become a major factor in the etiology of lung cancer, but many clinicians and patients do not pay high attention to it, resulting in cancer in some of them. Therefore, once a small lung nodule is found, its nature must be diagnosed and actively treated with regular follow-up.