Abstract: Understanding the change rule of plasma impedance in the process of magnetron sputtering discharge is conducive to regulating the impedance matching between power supply and load, so as to maximize the use of sputtering power and improve the coating quality. In order to study the changing trend of plasma impedance characteristics in the process of magnetron sputtering coating, V-I probe is used to measure the plasma impedance and the negative bias voltage of the electrode plate, and the effects of gas flow and sputtering power on the plasma impedance characteristics are studied. The results show that, under the experimental conditions in this paper, the plasma always presents capacitive reactance characteristics. When the gas flow rate increases, the real part R of the plasma impedance increases first and then decreases due to the ionization rate of argon, and the imaginary part X of the impedance decreases first and then increases due to the influence of secondary electrons and sheath. When the sputtering power increases, the influence of ohmic heating and random heating on the real part R of the plasma impedance increases all the time, while the influence of negative bias voltage and sheath on the imaginary part X of the impedance decreases all the time.