The disclosure discloses an authentication routing system and method for a cloud computing service and an authentication router. The method comprises the following steps: an authentication router registers a cloud computing service and saves the registration information of a cloud computing service registered successfully, wherein the registration information includes but is not limited to: an index number of a cloud computing service, an authentication mechanism chosen by the cloud computing service, an address of an authentication server address providing the authentication mechanism and a routing strategy of the authentication server; when a user terminal requests a cloud computing service, the authentication router receives an authentication request for the user terminal from the requested cloud computing service; and the authentication router routes the authentication request for the user terminal to a corresponding authentication server for authentication according to the saved registration information corresponding to the cloud computing service. Through the disclosure, a cloud computing service can provide a consistent user authentication experience and a relatively high authentication security level and effectively ensures the privacy security of the user when being used by the user.