How to obtain pathological evidence in early stage of peripheral type of lung cancer is always a difficult problem. The following methods can be considered: 1. Bronchoscopy, which can be performed to lavage and check for the presence of exfoliated cells. 2.Sputum cytology examination. 3, PET-CT examination to see if there is a metabolic increase. 4.Make preliminary judgment based on imaging characteristics. 5.The patient’s physical condition allows, open-chest exploration can be considered. 6.Check whether there are metastatic lesions in common metastatic organs of lung cancer such as brain, liver and bone.