A Carrier Aggregation, CA, based data transmission method, comprising: an evolved NodeB, eNB, configuring a user equipment with at least two Time Division Duplex Uplink and Downlink, TDD UL/DL, configuration sets, wherein each TDD UL/DL configuration set comprises at least one cell; and the eNB configuring a cell respectively in each TDD UL/DL configuration set as an Especial Cell, Ecell, that is configured to have all or part of functions of a Primary Cell, PCell; characterized in that, the eNB configuring a cell in each TDD UL/DL configuration set as an Ecell comprises: when the TDD UL/DL configuration set comprises only one cell, then configuring the cell as an Ecell; or when the TDD UL/DL configuration set comprises at least two cells, then configuring a cell with a highest channel quality as an Ecell or configuring a cell subject to a lowest interference as an Ecell or configuring a cell with the highest channel quality and subject to the lowest interference as an Ecell; and the eNB notifying the user equipment of a TDD UL/DL configuration in each TDD UL/DL configuration set and the Ecell in each TDD UL/DL configuration set; wherein the eNB notifying the user equipment of the Ecell in each TDD UL/DL configuration set comprises: the eNB notifying the user equipment of an identity, ID, of the Ecell in the TDD UL/DL configuration set by Radio Resource Control, RRC, signaling or a broadcast; or the eNB notifying the user equipment of Ecell-specific configuration information for the Ecell in the TDD UL/DL configuration set by RRC signaling; and wherein the eNB notifying the user equipment of the ID of the Ecell in the TDD UL/DL configuration set by RRC signaling or a broadcast comprises: the eNB sending an ID of a TDD UL/DL configuration of the TDD UL/DL configuration set, the ID of the Ecell in the TDD UL/DL configuration set and IDs of the other cells in the TDD UL/DL configuration set to the user equipment by the RRC signaling or the broadcast; or the eNB sending an ID of a TDD UL/DL configuration corresponding to each cell and the ID of the Ecell in the TDD UL/DL configuration set corresponding to the cell to the user equipment by the RRC signaling or the broadcast; wherein the Ecell-specific configuration information comprises one or more of: Hybrid Automatic Repeat Request, HARQ, ACK/NACK feedback resource configuration information, pathloss reference configuration information, and random access resource configuration information. an evolved NodeB, eNB, configuring a user equipment with at least two Time Division Duplex Uplink and Downlink, TDD UL/DL, configuration sets, wherein each TDD UL/DL configuration set comprises at least one cell; and the eNB configuring a cell respectively in each TDD UL/DL configuration set as an Especial Cell, Ecell, that is configured to have all or part of functions of a Primary Cell, PCell; characterized in that, the eNB configuring a cell in each TDD UL/DL configuration set as an Ecell comprises: when the TDD UL/DL configuration set comprises only one cell, then configuring the cell as an Ecell; or when the TDD UL/DL configuration set comprises at least two cells, then configuring a cell with a highest channel quality as an Ecell or configuring a cell subject to a lowest interference as an Ecell or configuring a cell with the highest channel quality and subject to the lowest interference as an Ecell; and the eNB notifying the user equipment of a TDD UL/DL configuration in each TDD UL/DL configuration set and the Ecell in each TDD UL/DL configuration set; when the TDD UL/DL configuration set comprises only one cell, then configuring the cell as an Ecell; or when the TDD UL/DL configuration set comprises at least two cells, then configuring a cell with a highest channel quality as an Ecell or configuring a cell subject to a lowest interference as an Ecell or configuring a cell with the highest channel quality and subject to the lowest interference as an Ecell; and the eNB notifying the user equipment of a TDD UL/DL configuration in each TDD UL/DL configuration set and the Ecell in each TDD UL/DL configuration set; the eNB notifying the user equipment of an identity, ID, of the Ecell in the TDD UL/DL configuration set by Radio Resource Control, RRC, signaling or a broadcast; or the eNB notifying the user equipment of Ecell-specific configuration information for the Ecell in the TDD UL/DL configuration set by RRC signaling; and wherein the eNB notifying the user equipment of the ID of the Ecell in the TDD UL/DL configuration set by RRC signaling or a broadcast comprises: the eNB sending an ID of a TDD UL/DL configuration of the TDD UL/DL configuration set, the ID of the Ecell in the TDD UL/DL configuration set and IDs of the other cells in the TDD UL/DL configuration set to the user equipment by the RRC signaling or the broadcast; or the eNB sending an ID of a TDD UL/DL configuration corresponding to each cell and the ID of the Ecell in the TDD UL/DL configuration set corresponding to the cell to the user equipment by the RRC signaling or the broadcast; the eNB sending an ID of a TDD UL/DL configuration of the TDD UL/DL configuration set, the ID of the Ecell in the TDD UL/DL configuration set and IDs of the other cells in the TDD UL/DL configuration set to the user equipment by the RRC signaling or the broadcast; or the eNB sending an ID of a TDD UL/DL configuration corresponding to each cell and the ID of the Ecell in the TDD UL/DL configuration set corresponding to the cell to the user equipment by the RRC signaling or the broadcast;