Abstract: Ruling by law and credibility exist side by side and support each other， i.e.， credibility is the foundation of ruling by law， which in turn is the guarantee of credibility. The credibility basis of cyberspace legalization consists of four aspects—credibility construction of network management institutions， credibility construction of network service providers， credibility construction of internet users， and credibility construction of network communities. The core for the credibility construction of network management institutions lies in the effective supervision of power， both internally and externally， and the supervision of leading cadres and authorities. The credibility construction of internet service providers includes credibility management， social order maintenance and protection of internet users rights and interests， whose key is to realize information credibility. The credibility construction of internet users calls for political， economic and cultural consideration， among which strengthening instruction and guidance is an effective way out. The credibility construction of network communities needs to start from “the very heart”， which requires the promotion and guarantee of the relevant systems and mechanisms.

Key words: internet, legalization, credibility