The invention relates to a sound intermediate frequency demodulator with a first demodulation unit and a second demodulation unit and a sound intermediate frequency demodulation method thereof. A sound inverse matrix operation unit is suitable for performing inverse matrix operation on the output of the sound intermediate frequency demodulator to generate a driving signal. The first demodulation unit demodulates a first carrier signal to generate a first demodulation signal in the sound inverse matrix operation unit; a second demodulation unit detects quality of a sound signal and demodulatesa second carrier signal to generate a second carrier signal to generate a second demodulation signal in the sound inverse matrix operation unit and/or a first demodulation unit; and when being idle, the second demodulation unit is programmed to select the corresponding standards in a plurality of preset standards relevant to the sound signal according to the quality of the sound signal, so that the sound intermediate frequency demodulator is programmed to demodulate the sound signal according to the corresponding standards.