Early stage of lung cancer may have no obvious symptoms, but when the disease develops to a certain extent, the following symptoms often appear: (1) Irritating dry cough. (2) Blood in sputum or bloody sputum. (3) Chest pain. (4) Fever. (5) Shortness of breath. When respiratory symptoms are not relieved by symptomatic treatment for more than 2 weeks, especially blood in sputum, irritating dry cough, or aggravation of existing respiratory symptoms, the possibility of lung cancer should be highly alerted. Most patients with early-stage lung cancer do not have obvious related positive physical signs. Imaging methods for lung cancer include X-ray chest radiograph, CT, magnetic resonance imaging (MRI), ultrasound, nuclear imaging, positron emission computed tomography (PET-CT) and so on. They are mainly used for lung cancer diagnosis, staging, re-staging, efficacy monitoring and prognosis assessment. In the diagnosis and treatment of lung cancer, one or more imaging methods should be selected reasonably and effectively according to different examination purposes.