The present invention relates to the communications field, and discloses an information transmission method and a device, which can resolve a problem of excessively high overheads of scheduling signaling of data retransmission in an unlicensed spectrum. A specific solution is as follows: writing a data retransmission identifier of a first carrier into a preset field of a physical downlink control channel; generating a data scheduling instruction of the physical downlink control channel; sending, on a second carrier, the data scheduling instruction of the physical downlink control channel to a receiving device; and sending data that is on the first carrier on the second carrier according to the data scheduling instruction of the physical downlink control channel. The present invention is applied to information transmission.