A method for monitoring impedance of an electrolyzer, wherein the electrolyzer is connected to a power supply, and the method comprises: acquiring a basic electric energy command and an impedance scanning electric energy command; controlling, according to the basic electric energy command and the impedance scanning electric energy command, the power supply to output an expected electric signal, wherein the expected electric signal comprises a direct current, DC, component signal and alternating current, AC, component signals, the DC component signal is used for normal operation of the electrolyzer, and frequencies of the AC component signals are preset frequencies in the impedance scanning electric energy command; acquiring, for each of the preset frequencies, a voltage vector and a current vector outputted by the power supply when outputting the DC component signal and an AC component signal having the preset frequency; and calculating (S 140), for each of the preset frequencies, according to the outputted voltage vector and the outputted current vector, an impedance value of the electrolyzer corresponding to the preset frequency, wherein the method is characterized in that the power supply comprises a first power supply and a second power supply, and the controlling, according to the basic electric energy command and the impedance scanning electric energy command, the power supply to output an expected electric signal comprises: controlling, according to the basic electric energy command, the first power supply to output the DC component signal in the expected electric signal; and controlling, according to the impedance scanning electric energy command, the second power supply to sequentially output the AC component signals respectively having the preset frequencies. acquiring a basic electric energy command and an impedance scanning electric energy command; controlling, according to the basic electric energy command and the impedance scanning electric energy command, the power supply to output an expected electric signal, wherein the expected electric signal comprises a direct current, DC, component signal and alternating current, AC, component signals, the DC component signal is used for normal operation of the electrolyzer, and frequencies of the AC component signals are preset frequencies in the impedance scanning electric energy command; acquiring, for each of the preset frequencies, a voltage vector and a current vector outputted by the power supply when outputting the DC component signal and an AC component signal having the preset frequency; and calculating (S 140), for each of the preset frequencies, according to the outputted voltage vector and the outputted current vector, an impedance value of the electrolyzer corresponding to the preset frequency, wherein the method is characterized in that the power supply comprises a first power supply and a second power supply, and the controlling, according to the basic electric energy command and the impedance scanning electric energy command, the power supply to output an expected electric signal comprises: controlling, according to the basic electric energy command, the first power supply to output the DC component signal in the expected electric signal; and controlling, according to the impedance scanning electric energy command, the second power supply to sequentially output the AC component signals respectively having the preset frequencies. controlling, according to the basic electric energy command, the first power supply to output the DC component signal in the expected electric signal; and controlling, according to the impedance scanning electric energy command, the second power supply to sequentially output the AC component signals respectively having the preset frequencies.