It is only ten years since E-cigarettes were first developed as a commercial product. E-cigarettes are consumed by inhalation through the respiratory tract and air exchange with lung. So it is not clear if E-cigarettes cause damage to the respiratory tract and other parts of the body. Additionally, the small sample sizes in the population survey and the epidemiological statistics analysis have limited the study of their safety. Under the current circumstances, it is of great importance to investigate the influence of E-cigarettes on human health. Furthermore, more information needs to be provided to the public in terms of guidance for the safe and reasonable use of E-cigarettes. For example, whether or not addiction will be induced after long-term use of E-cigarettes is a question that should be paid more attention. The safety of the equipment is another concern. Meanwhile, specific policies should be authorized by governments to guarantee the quality of production process, the specifications of the E-cigarette, and its safety evaluation. The current review provides relevant information useful for understanding the constitution, history and safety evaluation of E-cigarettes based on the existing literature.