Embodiments of the present invention provide a data transmission method based on cross-carrier scheduling. The method includes: determining a first downlink subframe according to a timing relationship of an uplink HARQ of a reference uplink and downlink configuration, where the first downlink subframe is used to indicate timing of sending uplink scheduling grant information of a first uplink subframe of a scheduled cell; transmitting the uplink scheduling grant information in a subframe of a scheduling cell corresponding to the first downlink subframe, under a circumstance that the subframe of the scheduling cell corresponding to the first downlink subframe is a downlink subframe, where an uplink and downlink configuration of the scheduling cell and an uplink and downlink configuration of the scheduled cell are different; and receiving or sending uplink data in the first uplink subframe. In the present invention, the cross-carrier scheduling may be implemented effectively.