A method is provided for transmitting data. The method includes: receiving at least one retransmission request, wherein a retransmission request is configured to request retransmission of the erroneous sub-data blocks in the previously transmitted data block; combining the sub-data blocks that need to be retransmitted into a target data block when the sub-data blocks that need to be retransmitted satisfy a predetermined condition; and sending the target data block to a second communication device.