After 1967, with the application of fiberoptic bronchoscopy (hereinafter referred to as fibronectomy) developed by Ikeda et al. to clinical practice, the advent of transbronchoscopic lung biopsy (TBLB), bronchoalveolar lavage (BAL) techniques and various interventional tools, the use of bronchoscopy in clinical practice has been further popularized and improved. At present, bronchoscopy can be used not only to diagnose and treat endotracheobronchial lesions, but also to evaluate peripheral lung diseases and even to help stage and guide the treatment of bronchopulmonary cancer. (I) Indications and contraindications of bronchoscopy