The present disclosure provides a method for an authentication system to provide authentication information for a web page, comprising: receiving a request for authentication information from a web page; judging whether the web page is redirected to through a relevant search engine; judging whether the web page satisfies a condition of displaying the authentication information; and providing the authentication information to the web page satisfying the condition. By providing authentication information to a web site through a search engine, with the combination of the authentication system with the relevant search engine, the reliability and security of authentication information are enhanced. Besides, the user may autonomously edit and manage the displaying pattern of the authentication information, such that the authentication information may be displayed in real time on the web page.