Early diagnosis of lung cancer is mainly made through the following five aspects: 1. imaging examination: chest X-ray, CT and MRI, which can understand the relationship between tumor size and lung lobes, lung segments, bronchi and blood vessels; PET-CT has a higher positive diagnosis for tumor; 2. repeated sputum examination for cancer cells: if positive results are obtained, it is a great guide for diagnosis and later treatment; 3. bronchoscopy 3.Bronchoscopy: direct observation of the lesion can be made, and biopsy histopathological examination can be taken at the same time, i.e., smear of bronchial secretion can be taken to check cancer cells; 4.Lung biopsy: smear of puncture material can generally obtain positive results and has diagnostic value; 5.Superficial lymph node puncture or biopsy: when lung cancer with unconfirmed lung lesion or with upper mediastinum widening is present, palpable lymph nodes on the neck clavicle, subcutaneous suspicious masses, and Puncture, aspiration or biopsy of suspicious cancerous lymph nodes in other areas may be performed to obtain pathological histological confirmation of the diagnosis.