The incidence of lung cancer is increasing in China, and more and more people die of lung cancer every year. Since this disease is difficult to be detected by patients in early stage, it always leads to miss the best treatment period. Let me introduce to you how to examine lung cancer. 1.Sputum exfoliative cytology examination The positive rate of this examination is 60%~80%, and about half of them can distinguish the types, which is convenient to take samples and easy to use. Patients should spit out the first and second mouthfuls of sputum after morning mouthwash, and sputum should be sent to the laboratory within half an hour after coughing up sputum from the deep part, and sputum with blood sputum should be selected for examination. Generally, it is appropriate to send sputum examination 4~6 times. 2.Fiber bronchoscopy Bronchoscopy is an effective means to diagnose lung cancer. Through bronchoscopy, the site and scope of tumor can be observed and the tissue can be taken for pathological examination. 3.CT examination Because the examination shows no overlap of cross-sectional anatomy, has high density resolution, and can examine the lung and mediastinum at the same time, it is most valuable for preoperative detection of lymph nodes in the lung, and can understand the site of enlarged lymph nodes, especially to discriminate n1, n2, etc. This is beneficial to the choice of treatment and helps to determine the surgery and scope. tumor, mediastinum, pleura) and quantitative measurement of ct values. The CT can be used to search for small lesions with a thin stratification of 1cm to avoid missing them. 4.magnetic resonance imaging The main feature of magnetic resonance (mri) compared with CT is to distinguish between vascular or substantial lesions without radiological damage and without contrast enhancement, and to show the trachea and bronchial tree next to the mass as well as the bronchus and blood vessels under compression and displacement. 5.Mediastinoscopy Mediastinoscopy is an effective means to diagnose mediastinal lymph node metastasis of lung cancer. If cytological diagnosis cannot be established by sputum cytology, bronchoscopy and needle biopsy, open-chest surgery should be considered, but the decision must be made after carefully weighing the pros and cons according to the patient’s age, lung function and surgical complications.