Abstract: The openness, virtuality and anonymity of network bring some illegal behaviors such as network rumors and defamation, which severely damage people’s reputation and social harmony The tort liability of Internet service providers should be distinguished based on their roles in the process of providing service Internet content provider assumes direct infringement liability, which is similar to general publishers Internet mediation service provider which consists of access service and platform service, generally assumes indirect contributory infringement They have the obligation to stop infringement after being informed by victim, while they should also take responsibility in the case of knowing the case clearly

Key words: Internet defamation, Internet service provider, citizen’s right of reputation, freedom of expression