Abstract: A multi-level pulse-amplitude modulation receiver system includes an analog equalizer, a digital equalizer, an automatic level tracking engine and an automatic gain controller. The analog equalizer and the automatic gain controller perform signal compensation on a multi-bit quasi-attenuation signal to generate a multi-level compensation signal. The digital equalizer receives the multi-level compensation signal, the positive threshold voltage and the negative threshold voltage, and thereby converts the multi-level compensation signal into a plurality of digital data. The automatic level tracking engine uses the digital data to generate a positive threshold voltage, a negative threshold voltage, at least two positive DC level voltages, and at least two negative DC level voltages, and the positive threshold voltage is an average of the two positive DC level voltages to avoid the nonlinear effect of the analog front end.