Studies and observations show that: smoking can cause the following diseases. 1, cardiovascular disease: smoking is associated with the onset of coronary heart disease, hypertension, sudden death, thrombo-occlusive vasculitis, smoking promotes the formation of blood clots and reduces the body’s ability to sense the aura of heart disease. 2, respiratory diseases: chronic bronchitis, emphysema, COPD and lung cancer. 3, digestive system diseases: peptic ulcer, gastritis, esophageal cancer, colon lesions, pancreatic cancer and stomach cancer. 4, cerebrovascular disease: smoking increases the risk of cerebral hemorrhage, cerebral infarction, subarachnoid hemorrhage. In addition, smoking can damage brain cells, impair memory, affect the thinking of the problem and cause mental disorders. 5, endocrine diseases: smoking 20 cigarettes / day, can increase the risk of diabetes 1 times. Smoking also promotes thyroid disease. 6, oral diseases: such as lip cancer, oral cancer, oral white spots, Candida albicans infection, oral mucosal pigmentation, oral odor, etc. 7, eye diseases mainly include: toxic optic neuropathy, visual hypoadaptation, macular degeneration, cataracts, etc.