A method and apparatus for Single Sign-on, wherein the user accesses a platform server and at least one service provider on the platform server. The method includes intercepting a request sent by the user via a client browser and extracting a domain name included in the request. If the domain name is an original domain name of the platform server, a global session ID is generated for uniquely identifying a session between the user and the platform server. A new domain name of the platform server associated with the global session ID is generated and the URL in the request is redirected to a new URL including the new domain name of the platform server. The request, including the new URL of the platform server, is forwarded to the platform server.