A carrier aggregation method and a carrier aggregation device are related to the field of communications technologies. The method includes: acquiring information of available spectrum resources; selecting an available frequency band less than a maximum design bandwidth and greater than or equal to a minimum design bandwidth as a base frequency band when the available frequency band exists in the available spectrum resources; determining a frequency band with a width being the maximum design bandwidth, where the frequency band with the width being the maximum design bandwidth has a center frequency which is an integral multiple of a minimum channel raster and is the closest to a center of the base frequency band; and determining an aggregated carrier by using the frequency band with the width being the maximum design bandwidth.