The present invention discloses a method and device for data transmission based on carrier aggregation (CA) technology. The method and device are used for ensuring that user equipments can work normally, when the multiple cells aggregated from the user equipments supporting CA technology have different time division duplex (TDD) uplink/downlink (UL/DL) configurations. The method includes: a base station configures at least two time division duplex uplink/downlink carrier TDD UL/DL configuration collections for the user equipments, wherein each TDD UL/DL configuration collection includes at least one cell; the base station respectively configures one cell in each TDD UL/DL configuration collection to be an especial cell (Ecell).