Smoking cessation is the most effective way to prevent cardiovascular disease, so it is strongly recommended by guidelines for the prevention and treatment of cardiovascular disease . However, nicotine addiction makes it difficult for most people to quit smoking . Therefore, the current methodology of quitting smoking is a combination of nicotine replacement with the drugs that include nicotinic receptor agonists and behavioral therapy. In conjunction with this treatment, electronic smoke inhalation of nicotine simulates the effect of traditional cigarette smoking. As a result, more and more consumers prefer E-cigarettes when they quit smoking. It is undeniable that E-cigarettes rather than traditional tobacco are much more effective for some people to achieve smoking cessation. However, some people will become a “double user”, namely they smoke both traditional cigarettes and E-cigarettes, especially in places where smoking traditional cigarettes is prohibited. This does not help to quit smoking, but rather leads to greater harm from smoking. Because of the “harmless” nature of E-cigarettes, tobacco users may reuse tobacco products. E-cigarettes may also be a potential way for adolescents or non-smokers to use tobacco, and the use of E-cigarettes may also be the gateway to other drugs or harmful substances. Moreover, users of E-cigarettes are less likely to quit smoking than those who have never used it . As early as 19 September 2008, the WHO declared that E-cigarettes were not proven to be effective for nicotine replacement therapies, and there was no scientific evidence that the product was safe and effective . Most importantly, nicotine is a highly addictive substance. If it cannot be strictly and carefully controlled, the function of the E-cigarette as a tool for nicotine replacement for the purposes of smoking cessation will not be fully achieved . E-cigarettes are packaged as harmless smoking-cessation products by sellers with the suggestion that the amount of nicotine in the e-liquid be gradually reduced, which would help smokers get rid of their nicotine dependence and achieve the goal of quitting smoking . However, the nicotine content of some E-cigarettes is not consistent with the labeling . In the process of smoking E-cigarettes, few people are able to get standardized guidance. Generally, the content of nicotine in the e-liquid is added quantitatively. In order to increase the number of users, different manufacturers have added various flavors of spices, many of which have not been approved by the authorities. Therefore, the efficacy of E-cigarettes for smoking cessation requires further research and demonstration.