The invention discloses an automatic audio signal gain control method and a device. The method comprises steps that an amplitude zero crossing point is identified in to-be-processed audio signals, and parts among adjacent zero crossing points are determined to be zero crossing intervals; at least one gain adjustment interval is determined according to the zero crossing intervals; if an audio is determined to be an effective audio according to the audio signal amplitude in a present gain adjustment interval, adjustment gain of the present gain adjustment interval is determined according to an audio signal peak value in the present gain adjustment interval; an amplitude of audio signals of the present gain adjustment interval is adjusted according to the adjustment gain and is further outputted. The method is advantaged in that gain adjustment on the audio signals in a time domain can be carried out, moreover, a distortion degree of the audio signals in a frequency domain can be reduced to a great degree, and the effect of improving user experience is realized.