Infrared detectors often need to accumulate more infrared signals by extending the integration time, which can make the integration capacitor of the traditional analogue domain readout circuit saturate prematurely, and digital pixel readout circuits can effectively solve this problem. Currently, pulse frequency modulation-based A/D conversion structure is widely used in pixel-level ADC solutions. As an important component of pulse frequency modulation-based A/D conversion units, the performance of comparators directly affects the performance of ADCs. In this paper, a comparator with hysteresis function is designed for digital pixel infrared readout circuits with low noise and low power consumption. The design is based on 0.18 μm CMOS process, and verified by simulation to have a good degree of conformity compared with the design objectives.