Abstract: An authentication method is applied in a gateway group comprising an authentication gateway and at least one data gateway. The gateway group receives a connection request from a user terminal, and determines whether there is an authentication record on the user terminal in an authentication list. The gateway group provides access service for the user terminal, if there is the authentication record. The gateway group sends an authentication request to an authentication authorization accounting (AAA) server and receives an authentication response from the AAA server, upon no authentication record. The gateway group provides access service for the user terminal, upon receiving a passing authentication response, and storing as the authentication record. The gateway group rejects the access for the user terminal, upon receiving a denying authentication response.