Lung cancer is the most common primary malignant tumor of the lung. Most lung cancers originate from the mucosal epithelium of the bronchus, so it is also called bronchial lung cancer. In the diagnosis of lung cancer, fiberoptic bronchoscopy is essential. Since lung cancer is a bronchial tumor, especially those early tumors are difficult to be detected by X-ray or CT film alone, bronchoscopy, which can directly observe the lesions in the trachea, becomes a very effective means. At present, a large number of lung cancer patients are diagnosed by bronchoscopic biopsy or cytology.