A retransmitted data sending method, applied to a transmit end, comprising: sending a first aggregate Media Access Control protocol data unit, A-MPDU, wherein the first A-MPDU comprises M A-MPDU subframes and M tail bit parts, one tail bit part corresponds to one A-MPDU subframe, and M is greater than or equal to 1; determining N MPDUs in the first A-MPDU that need to be retransmitted, wherein the N MPDUs are respectively comprised in N A-MPDU subframes of the first A-MPDU; and N is greater than or equal to 1, and M is greater than or equal to N; and sending a second A-MPDU, wherein the second A-MPDU comprises the N A-MPDU subframes and N tail bit parts corresponding to the N A-MPDU subframes; wherein one tail bit part comprises at least 6 bits, and the at least 6 bits are a preset value, and wherein the second A-MPDU is carried in a second physical protocol data unit, PPDU, the second PPDU comprises a physical preamble, characterised in that: the physical preamble comprises one or more of the following: a modulation and coding scheme indication, wherein if the modulation and coding scheme indication is a special value, the special value is used to indicate that the second PPDU comprises only retransmitted MPDUs and does not include a non-retransmission MPDU; and tail bit part location indication: used to indicate a location of a tail bit part corresponding to a last A-MPDU subframe in the N A-MPDU subframes. sending a first aggregate Media Access Control protocol data unit, A-MPDU, wherein the first A-MPDU comprises M A-MPDU subframes and M tail bit parts, one tail bit part corresponds to one A-MPDU subframe, and M is greater than or equal to 1; determining N MPDUs in the first A-MPDU that need to be retransmitted, wherein the N MPDUs are respectively comprised in N A-MPDU subframes of the first A-MPDU; and N is greater than or equal to 1, and M is greater than or equal to N; and sending a second A-MPDU, wherein the second A-MPDU comprises the N A-MPDU subframes and N tail bit parts corresponding to the N A-MPDU subframes; wherein one tail bit part comprises at least 6 bits, and the at least 6 bits are a preset value, and wherein the second A-MPDU is carried in a second physical protocol data unit, PPDU, the second PPDU comprises a physical preamble, characterised in that: the physical preamble comprises one or more of the following: a modulation and coding scheme indication, wherein if the modulation and coding scheme indication is a special value, the special value is used to indicate that the second PPDU comprises only retransmitted MPDUs and does not include a non-retransmission MPDU; and tail bit part location indication: used to indicate a location of a tail bit part corresponding to a last A-MPDU subframe in the N A-MPDU subframes. a modulation and coding scheme indication, wherein if the modulation and coding scheme indication is a special value, the special value is used to indicate that the second PPDU comprises only retransmitted MPDUs and does not include a non-retransmission MPDU; and tail bit part location indication: used to indicate a location of a tail bit part corresponding to a last A-MPDU subframe in the N A-MPDU subframes.