Abstract: [Purpose/Significance] It can provide useful enlightenment for online public opinion research, platform optimization and governance to empirically evaluate whether and how the display of IP localization policy affect public opinion comments.[Design/Methodology] Based on self-monitoring theory and privacy calculus theory, the research model and hypothesis were constructed. Taking the launch of the "IP localization" function of Weibo as the quasi-natural experiment, the method of Difference-in-Difference（DID）and breakpoint regression model were used to explore the policy effect of IP localization policy on public opinion comments. [Findings/Conclusion] The policy induces the effect on users' self-monitoring and users' risk perception, which not only improve the overall affective tendency, readability and empathy of comments, but also significantly inhibites the affective polarity of comments. This conclusion is still valid after a series of robustness tests. The policy effect is significantly different among different user groups. Compared with the users in the hot center of the event, the display of IP location can prompt the users in the non-hot center to make changes. The policy also exacerbates geographic discrimination in comments. [Originality/Value] This study reveals the impacts of IP localization policy on public opinion comments, povides a new perspective for improving the internet environment, and enriches the relevant research in the field of IP localization and the influencing factors of public opinion comment behavior.

Key words: IP localization, Public opinion comments, Privacy calculus theory, Geographic discrimination, Difference-in-Difference