According to the application requirements of the weak energy harvesting system, a folded low voltage, low power hysteresis comparator with a wide voltage range was designed. In the input stage and output stage of the comparator, the biasing circuit and internal node were used to bias the tail transistors respectively, which realized the automatic adjustment of the tail current according to the variation of the practical working voltage. So the power consumption and the output response time were decreased. Based on a 0.18 μm CMOS process, the simulation results showed that the comparator could work normally in the range of 0.8~1.2 V supply voltage, the hysteresis voltage was adjustable in the range of 15~70 mV, and the lowest power consumption was 0.15 μW.