Abstract: Driven by emerging science and technology, e-cigarettes atomize liquid smoke in a variety of ways to deliver nicotine or other substances to the respiratory system. The special product structure and mechanism of e-cigarettes cause uncertain risks, and how to balance the development of new e-cigarette technologies and prevent unknown risks has become a difficult point in e-cigarette supervision. The precautionary principle is not only applicable to the regulation of e-cigarettes, but also necessary to apply it because of the scientific uncertainty and significant damage caused by e-cigarettes. China’s current e-cigarette supervision should absorb the principle of risk prevention and further improve it to establish the legitimacy of regulatory norms.