In recent years, the incidence rate of cancer in China has been increasing, and the incidence rate of lung cancer has reached 61.4 per 100,000, making lung cancer the number one cancer in China. What is more worrying is that the incidence rate of lung cancer is still on a rising trend, and the number of young adults among the incidence group is increasing. A Meta-analysis on the main risk factors of lung cancer in Chinese population shows that the main factors affecting the occurrence of lung cancer in Chinese population are mental factors, smoking, indoor environmental pollution, respiratory diseases and family history, vegetable and fruit intake, etc. Since the 1950s, a large number of epidemiological studies worldwide have confirmed that smoking is the primary risk factor for lung cancer, and 87% of lung cancer deaths are caused by smoking, which can produce more than 40 kinds of carcinogenic substances, among which the main ones closely related to lung cancer are polycyclic aromatic hydrocarbons, benzene, arsenic, propylene, nicotine (nicotine), carbon monoxide, and tobacco tar, etc. These These carcinogens can lead to DNA damage of bronchial epithelial cells, activation of certain oncogenes, mutation and inactivation of oncogenes through different mechanisms, resulting in the transformation of cellular genetic information into cancer. It is well established that smoking causes cancer. Epidemiological surveys show that smoking is one of the important causative factors of lung cancer, and the risk of lung cancer in smokers is 13 times higher than that in nonsmokers, and 45 times higher than that in nonsmokers if they smoke more than 35 cigarettes per day. The mortality rate of lung cancer among smokers is 10 to 13 times higher than that of nonsmokers. About 85% of lung cancer deaths are caused by smoking. Smokers who are also exposed to chemical carcinogens (such as asbestos, nickel, uranium, and arsenic) have a higher risk of developing lung cancer. The polycyclic aromatic hydrocarbons in tobacco smoke need to be metabolized by polycyclic aromatic hydrocarbon hydroxylase before they are cytotoxic and mutagenic, and the concentration of this hydroxylase is higher in smokers than in nonsmokers. Smoking decreases the activity of natural killer cells, thereby reducing the body’s ability to monitor, kill and remove tumor cells, which further explains why smoking is a high risk factor for the development of many cancers.