Lung cancer is the most common malignant tumor in the world, and the incidence and mortality rate are the first among malignant tumors. The treatment effect of lung cancer is closely related to the early and late detection. As lung cancer symptoms appear late, many of them are discovered by chance, and 80% of the clinical symptoms are already at advanced stage, which leads to a loss of surgical opportunity, and the 5-year survival rate is only 16%, while the 5-year survival rate of early stage lung cancer can reach 90%. The only way to improve the quality of life and extend the survival time of lung cancer patients is early detection and early treatment, and the best method for early detection is low-dose CT screening. The 2013 U.S. Lung Cancer Screening Guidelines ultimately recommend annual lung cancer screening using low-dose CT for patients aged 50-80 years who are at high risk for lung cancer. Patients at high risk for lung cancer are those who have a history of smoking 15 cigarettes/day and are still smoking or have quit smoking within 15 years; or have a family history of lung cancer. The main reasons are: ① passive smoking; ② air pollution, PM2.5 from haze; ③ the hazard of kitchen fumes. It is recommended that people over 40 years of age, regardless of gender and whether they smoke or not, should be targeted for lung cancer screening.