The present invention provides a data transmission method, device, and system, which relate to the communications field and can improve data transmission efficiency. The method includes: sending, by a secondary base station, first information to a primary base station, where the first information includes one of the number x of first PUCCH code channel resources, the number x of first data blocks sent by the secondary base station to a user equipment UE, and a first channel code word; sending, by the secondary base station, identifiers of the x first PUCCH code channel resources and the x first data blocks to the UE; and receiving, by the secondary base station, a feedback from the primary base station, where the feedback is received by the primary base station from the UE by using the first PUCCH code channel resource.