A transmit end modulation adjustment method, comprising: determining a retransmission request rate of each group of subchannels according to a retransmission request received through at least two groups of subchannels, determining at least one group of subchannels whose retransmission request rate is not a hundred percent, and determining noise variation information according to an initial signal-to-noise ratio margin of the at least one group of subchannels, wherein each group of subchannels comprises at least one subchannel, and the initial signal-to-noise ratio margin of each group of subchannels is different from that of each other group of subchannels; and adjusting a signal-to-noise ratio margin of each group of subchannels according to the noise variation information, characterized in that, the determining noise variation information according to the initial signal-to-noise ratio margin of the at least one group of subchannels is specifically: generating the noise variation information according to a smallest initial signal-to-noise ratio margin in the initial signal-to-noise ratio margin of the at least one group of subchannels; and correspondingly, the adjusting a signal-to-noise ratio margin of each group of subchannels according to the noise variation information is specifically: increasing the signal-to-noise ratio margin of each group of subchannels according to the noise variation information. determining a retransmission request rate of each group of subchannels according to a retransmission request received through at least two groups of subchannels, determining at least one group of subchannels whose retransmission request rate is not a hundred percent, and determining noise variation information according to an initial signal-to-noise ratio margin of the at least one group of subchannels, wherein each group of subchannels comprises at least one subchannel, and the initial signal-to-noise ratio margin of each group of subchannels is different from that of each other group of subchannels; and adjusting a signal-to-noise ratio margin of each group of subchannels according to the noise variation information, characterized in that, the determining noise variation information according to the initial signal-to-noise ratio margin of the at least one group of subchannels is specifically: generating the noise variation information according to a smallest initial signal-to-noise ratio margin in the initial signal-to-noise ratio margin of the at least one group of subchannels; and correspondingly, the adjusting a signal-to-noise ratio margin of each group of subchannels according to the noise variation information is specifically: increasing the signal-to-noise ratio margin of each group of subchannels according to the noise variation information. generating the noise variation information according to a smallest initial signal-to-noise ratio margin in the initial signal-to-noise ratio margin of the at least one group of subchannels; and correspondingly, the adjusting a signal-to-noise ratio margin of each group of subchannels according to the noise variation information is specifically: increasing the signal-to-noise ratio margin of each group of subchannels according to the noise variation information. increasing the signal-to-noise ratio margin of each group of subchannels according to the noise variation information.