Abstract: In COVID–19 epidemic prevention and control, isolation of close contacts in accordance with the law is an important measure to cut off the transmission of the virus and ensure the health and safety of the citizens. Balancing public power and private rights, the principle of proportionality plays a significant role in determining the level of infectious disease prevention and control measures, guiding and regulating the form of administrative emergency power, and in improving the mechanism of civil right protection in multiple dimensions. Through the analysis of problems in the application of the principle of proportionality, such as the over-expansion of the scope of close contacts, the disorder of "designated place", the unclear procedure and degree of compulsory measures, we conclude that the principle of proportionality should be followed in the application of isolation norms to clarify the inherent logic of legitimacy, appropriateness, necessity and balance. Applying the principle of proportionality in clarifying the boundaries of close contacts and in defining the "designated places" contributes to the balance between state power and individual rights, and balance between private rights of close contacts and public interests.

Key words: COVID–19, proportional principle, close contacts, isolation rules, compulsory measures