This application provides example data retransmission methods and communication apparatuses. One example method includes receiving a physical protocol data unit (PPDU) by a first device and from a second device, where the PPDU includes a signaling field and a data field, the data field includes retransmitted data and newly transmitted data, the signaling field includes first indication information, or the signaling field comprises the first indication information and second indication information, the first indication information indicates a first modulation and coding scheme (MCS) and a first coding mode that are used for the newly transmitted data, and the second indication information indicates a second MCS and a second coding mode that are used for the retransmitted data. The PPDU is demodulated based on the signaling field.