A self-adaptive current mode amplitude shift-keying (ASK) demodulator was proposed to meet the requirements of the low-voltage RFID tags. The demodulator improves the dynamic demodulation performance by converting voltage signal to more detectable current signals, employing two-stage current-peak-hold technique, and introducing leak circuit. It could operate under the supply voltage from0.6V to 1.8V, the input carrier magnitude is from 250 mV to 1.1V, and the modulation depth is from 20% to 100%. Under the voltage supply of 1.8 V, its dynamic demodulation is from 80 nA to 3.96μA. The demodulator is designed and implemented with 0.18μm CMOS process technology.