The present invention discloses a data transmission method and device for an inter-station carrier aggregation system. The method includes the following steps that: a first base station which provides services for user equipment determines a first UL-DAI value for the user equipment; and if the first base station receives a second UL-DAI value sent by a second base station which provides services for the user equipment, the first base station determines the maximum one in the first UL-DAI value and the second UL-DAI value as a UL-DAI value configured for the user equipment by the first base station, wherein the second UL-DAI value is a UL-DAI value which is determined by the second base station for the user equipment. Since the UL-DAI value is determined for the same user equipment through interaction between the base stations, the UL-DAI values configured by different base stations for the user equipment are matched, and therefore, the data transmission process of the user equipment under the scheduling of the different base stations can be ensured, and the throughput of the system can be further improved.