In thoracic surgery clinics, we often encounter patients with lung nodules found on physical examination and ask with nervousness, “Is it lung cancer? There are benign and malignant nodules in the lung. Benign nodules include tuberculosis spheres, benign lung tumors (malignant tumors, lipomas, etc.), lung inflammation (spherical pneumonia, inflammatory pseudotumors), lung cysts, lung isolation disease, etc. Malignant nodules include primary malignant tumors (lung cancer, carcinoid tumors) and secondary malignant tumors (metastatic cancer). Firstly, ask if there are any recent uncomfortable symptoms, such as cough, coughing, hemoptysis, chest pain, dyspnea, fever, wasting, hoarseness, etc. Next, review the past medical history, especially whether you have had other types of malignant tumors. If there was a previous chest film or chest CT, find it and compare it with the film of this examination to see if the nodule is new or existed before. Pathologic diagnosis is the ultimate basis for determining the nature of the nodule in the lung. If the patient has sputum, sputum can be checked to find tumor cells and tuberculosis bacteria. If there is pleural effusion, puncture to extract the effusion for cytological examination. Fiberoptic bronchoscopic biopsy is indicated for central lesions close to the large airways, while CT-guided puncture is indicated for peripheral lesions close to the chest wall. Cytology and biopsy, due to the limitation of the volume and site of sampling, may also have negative results for true tumor lesions, when other means such as blood tumor markers (SCC, CYFRA21-1-squamous carcinoma, CEA-adenocarcinoma, NSE, ProGRP-small cell carcinoma), isotope pro-tumor imaging, PET-CT, tuberculin skin test (PPD ), blood sedimentation, blood TB antibodies, etc. indirectly to provide diagnostic reference advice. History of previous tumors in other parts of the body is important for the diagnosis of metastatic tumors in the lung. If the nature of the lesion is still not determined after the above examination process, two different treatment methods can be used according to the patient’s wishes. Otherwise, surgical treatment should still be taken. If inflammation is considered to be present, the patient should be reviewed after 1-2 weeks of anti-infection treatment. This is indicated for patients who are not physically able to tolerate surgery, or who have fears and doubts about surgery. The second is surgical exploration, through thoracoscopy or small incision open chest method, local excision of lesions intraoperative rapid pathological examination, if benign, surgery is over, if malignant, expand the scope of excision, radical surgery. It is suitable for patients who are physically able to tolerate the surgery and also have the will to operate. Before surgery, two aspects of patient evaluation are needed: first, cardiopulmonary function to determine the patient’s tolerance to surgery, and second, clinical stage of the tumor, except for possible distant metastases, and patients who have metastases are not suitable for radical surgery.