Excitation regulator plays a positive role in improving the voltage regulation characteristics of the generator, but the analysis of the current measurement is not enough. In order to study current measurement value of excitation regulator characteristics influence were established two simulation models of generator automatic excitation voltage and fixed excitation voltage, and the Thewenin’s equivalent circuit of excitation regulation device in the current analysis. Analysis and simulation results show that the excitation regulator in the stable machine terminal voltage and intensified between the generator and the system oscillation, and the introduction of the current measurement value is by the generator voltage and system voltage vector difference oscillatory was characteristic of low frequency oscillation of the alternating current, the current will exacerbate the oscillation between the generator and the system. Finally, the correctness of theoretical analysis is verified by further simulation.