The highest diagnosis of lung cancer is pathological diagnosis. There are two main types of lung cancer pathologically: non-small cell lung cancer, which originates from epithelial cells (located in the inner layer of the airway, which can secrete mucus and play the role of lubricating and protecting lung tissues), is the main type; the other type is small cell lung cancer, which originates from neural or hormone-secreting cells of the lung. The term “small cell” refers to the size and shape of the cells under the microscope. Generally speaking, patients with clinical diagnosis of lung cancer based on clinical manifestations, laboratory tests and especially imaging should be diagnosed pathologically as soon as possible. Open-chest exploration is suitable for patients with high suspicion of lung cancer in imaging, but no cancer cells are found in sputum cytology and tracheoscopy, and the patient is not suitable for lung puncture due to various reasons.