Lung cancer is a serious health hazard and a disease with high morbidity and mortality in China. In recent years, due to environmental changes and changes in people’s lifestyle, more and more patients are suffering from lung cancer. Understanding the causes of lung cancer can help people understand the disease and keep away from the hazards of lung cancer triggering factors, so that we can pay attention to it and achieve the purpose of lung cancer prevention. Smoking is an important cause of lung cancer, which has been recognized by most experts and the general public. Studies have found that men who smoke more than 2 boxes a day have more than 20 times the risk of developing lung cancer than normal people. The longer you smoke and the more you smoke, the greater the risk of lung cancer. Second, low intake of fresh vegetables Vegetables and fresh fruits play a great role in preventing the development of lung cancer, and the greater the intake, the more obvious the preventive effect. Not consuming vegetables for a long time will also aggravate the initiation of lung cancer. In addition, fried foods and preserved foods also increase the risk of lung cancer development. III. History of respiratory diseases Data show that previous history of lung diseases such as asthma, chronic obstructive pulmonary emphysema, pneumonia and tuberculosis are dangerous causes of lung cancer. These lung diseases often develop and deteriorate for various reasons leading to malignant transformation of lung tissue cells and producing lung cancer, among which tuberculosis is most closely related to the development of lung cancer. Spiritual factors: Spiritual factors are an important cause of lung cancer, and long-term mental depression has a great impact on the occurrence and development of the disease. Investigation found that the chance of getting lung cancer for people with mental depression is many times higher than that of the general population. Meanwhile, a negative and pessimistic state of mind can aggravate the condition of lung cancer. Age factor: middle-aged and old people are the high-risk group of lung cancer because with age, the immune organ thymus gradually atrophies, various organs gradually age, and various cells are prone to mutation, which are all factors of lung cancer. Endocrine factors: The occurrence of lung cancer is also related to endocrine, mainly due to factors such as metabolism, endocrine disorders and decline of immune function of the body, which lead to malignant changes of lung cells and produce lung cancer. Genetic factors: The incidence rate of lung cancer is higher than normal for people with lung cancer in their families, and genetic factors are important factors leading to lung cancer.