Lung cancer is the first incidence rate among malignant tumors in China, and also the first lethal factor. According to the data of previous years, the incidence rate of lung cancer is from 30 per 100,000 to 283 per 100,000, with an average of about 51 per 100,000. The national incidence and mortality rate of lung cancer is the first, and the mortality rate of lung cancer patients has ranked the first among malignant tumor deaths for 18 consecutive years, whether in urban or rural areas. Currently, there are about 800,000 lung cancer patients diagnosed each year, and about 650,000 patients die from lung cancer each year. Although it has become the number one killer of malignant tumor deaths in China, the total incidence of lung cancer in China is expected to reach 1 million patients by 2025, making it the number one lung cancer country in the world. According to the U.S. lung cancer research data, if no effective measures are taken, the incidence and mortality rate of lung cancer in China will rise to 4 million and 3 million by 2020, and 5 million and 3.5 million by 2030. The rate of increase is 26.9% per year. Currently, lung cancer is mainly screened by selecting high-risk groups, which have the following three conditions at the same time: age 40 or older, smoking index greater than 400 cigarettes/year, and quit smoking less than 15 years. Screening in patients with such conditions is more meaningful and has a higher detection rate. It is recommended to do low-dose spiral CT screening once a year, which can detect 80% of early lung cancer patients.