Embodiments of the present invention provide a cell access processing method and apparatus and a communication system. In a cell access processing method, an access request message is sent by a terminal. The access request message includes identification information of the terminal. A CSG information request message is sent to a CSG subscription information server of a roaming network. The CSG information request message includes the identification information of the terminal. A CSG information response message is sent by the CSG subscription information server according to the CSG information request message. The CSG information response message includes CSG information corresponding to the identification information of the terminal. Access control is performed on the terminal according to the CSG information.