A method, base station, terminal and communication system for updating component carriers are provided. Wherein, status information of the terminal, base station and/or component carrier is acquired; whether the status information accords with the predetermined condition is determined; an old component carrier is replaced by a new component carrier, or a new component carrier is added in the even that the predetermined condition is met. With the embodiments of the present invention, the component carrier which the terminal would use is updated more effectively.