Abstract: The development of precision advertising cannot be separated from the legitimate use of personal information. On the basis of clarifying the technical logic of precision advertising and the relationship between cookies and personal information protection. This paper uses text analysis method to conduct in-depth analysis on the contents of cookie technology in the 100 mobile app privacy policies commonly used by domestic users, and finds that the overall app privacy policy in China has made considerable progress compared with the past, especially after the promulgation of the personal information protection law. There is still significant room for improvement in the protection of personal information in precision advertising, which can be improved from the following four directions of the basic principles of privacy policy, consent mode, language expression and user rights. With the help of the government, industry and enterprises, we can jointly promote the balance between the subject of personal information protection and the subject of privacy policy formulation, and promote the healthy and sustainable development of the advertising industry.

Key words: Precise advertising, Behavior targeted advertising, Privacy policy, Cookie technology, Personal information protection