The accurate measurement of system capacitance current is the precondition and key factor for the correct tuning of the arc suppression coil in the resonance grounding system. On the basis of analyzing the existing problems in the capacitor current measurement method of distribution network, a new method for capacitor current measurement is proposed. By changing the inductance value of the arc suppression coil, the amplitude and phase of the neutral point displacement voltage and neutral point current of the system are measured before and after changing the inductance value. According to the formula, the total capacitance and conductance of the system are calculated. And then the rated capacitor current of the system is calculated. Finally, the MATLAB simulation proves that the method can achieve high measurement accuracy. The method is easy to operate and simple to calculate, and it can be used for the tuning calculation of arc suppression coil.