Lung cancer occurs in the bronchial mucosa or glands, also known as bronchial lung cancer. In the past 50 years, many countries have reported that the incidence of lung cancer has increased significantly. Among male cancer patients, lung cancer has ranked first, and the incidence rate in women has also increased rapidly, accounting for the second or third most common malignant tumors in women. The male-female incidence ratio is 3~5:1, and the age of onset is mostly between 60-79 years old. The cause of lung cancer is still not completely clear. A large amount of data shows that long-term heavy smoking is an important pathogenic factor of lung cancer. For those who smoke more than 40 cigarettes a day for many years, the incidence of squamous cell carcinoma and undifferentiated cancer of the lung is 4 to 10 times higher than that of non-smokers. The incidence of lung cancer in urban residents is higher than that in rural areas, which may be related to air pollution and carcinogens contained in smoke. Therefore, non-smoking should be advocated and urban environmental sanitation work should be strengthened.