A CT examination can detect occupying lesions in the lung and has an 80% confirmation rate. Lung cancer mainly appears on CT as soft tissue masses in the lungs with indistinct borders and burrs. Inflammation of the lung mainly appears as sheet-like exudative changes, and tuberculosis mainly occurs as exudative changes in both upper lungs, or called ground glass nodules, with pleural effusion or pleural thickening, etc. However, CT of lung is only an imaging diagnosis, and it is necessary to do fiberoptic bronchoscopy or CT-guided mass aspiration biopsy to clarify whether it is lung cancer or what type of lung cancer pathology it is. Therefore, if occupying lesions are found in lung CT, or middle-aged men with long-term smoking history, accompanied by coughing, coughing and blood in sputum, pathological examination must be done in time to confirm the diagnosis of lung cancer.