Lung cancer should be prevented at three levels. The first level of prevention, also known as etiological prevention, is to take measures against the cause of the disease before it occurs, to strengthen research on the cause of the disease and reduce risk factors, which is the fundamental of the first level of prevention. The second level of prevention, also known as the three early prevention, includes early detection, early diagnosis and early treatment. Tertiary prevention is a measure taken in the clinical stage of the disease to reduce the harm of the disease, which mainly includes symptomatic treatment and rehabilitation treatment, aiming to prevent disability and promote functional recovery, so as to improve the quality of patients’ survival, prolong their lives and reduce the death rate of the disease. The etiology and causative factors of lung cancer are well researched, mainly including smoking, environmental pollution, occupational factors and genetic susceptibility. Since lung cancer progresses rapidly with poor prognosis and lacks effective secondary prevention measures, primary prevention should be the first priority in the prevention of lung cancer.