A data processing method for a hybrid automatic repeat request (HARQ) is provided. Specifically, modulation can be performed according to a constellation rearrangement version (CRV) to generate a sub-packet for an incremental redundancy HARQ (IR-HARQ). When a constellation symbol modulated according to the CRV is segmented into an even symbol and an odd symbol for a plurality of transmit antennas, an identical CRV is determined for a pair of the even symbol and the odd symbol subsequent to the even symbol. When the constellation symbol modulated according to the CRV is transmitted to a receiving side, a newly generated sub-packet is retransmitted upon receiving a non-acknowledgement (NACK) signal.