The invention relates to a digital receiver and a related method thereof. The digital receiver comprises an analog front end circuit, an automatic gain controller, a compensation circuit and a demodulator, wherein the analog front end circuit is used for receiving an input signal, adjusting an average amplitude of the input signal and converting the adjusted input signal according to a control signal to generate a digital signal; the automatic gain controller is used for generating the control signal according to the digital signal and feeding back the control signal to the analog front end circuit; the compensation circuit is used for detecting the average amplitude of the digital signal to generate a detection result, and determining whether to compensate the average amplitude of the digital signal according to the detection result so as to generate a compensated digital signal; and the demodulator is used for demodulating the compensated digital signal to generate an output signal.