Embodiments of the present invention provide a method, a device, and a system for configuring a component carrier in a carrier aggregation scenario. The method for configuring a component carrier in a carrier aggregation scenario includes: obtaining information about a component carrier supported by a UE; selecting a candidate component carrier according to the information about the component carrier and configuring a resource parameter that is applied to the candidate component carrier to form configuration information about the candidate component carrier; and delivering the configuration information about the candidate component carrier to the UE. In the embodiments of the present invention, a base station may select a candidate component carrier for the UE according to obtained component carrier support information and perform resource configuration, so that the UE can accurately know to which component carrier a resource parameter is applied, and thus a data transmission error may be reduced.