Abstract: The plasma impulse source generated by the "liquid-electric effect" has great application value in the direction of rock fragmentation, geological guidance, location determination, etc. At present, there is still a lack of further understanding of the correlation between charging voltage and plasma discharge characteristics and impulse wave characteristics in the discharge circuit. Based on the experimental platform of underwater plasma discharge, a simulation model of underwater plasma impulse source is established to compare and analyze the measured and simulated results of typical voltage, current and impulse waveform of plasma impulse source discharge. Subsequently, the discharge characteristics and impulsive waveform characteristics at different charging voltages are studied by this simulation model. The results show that when the charging voltage is increased from 15 kV to 25 kV, the peak impulse strength increases by 31.9% and the impulse energy increases by 53.8%, and the conversion efficiency decreases by 28.4% because the rate of increase of external circuit energy is greater than the rate of increase of impulse energy. By varying the charging voltage to predict the impulsive waves, the intensity, energy loss and energy conversion efficiency of the impulsive waves under different charging voltages are compared and analyzed. It provides a reference basis for further research on the optimal charging voltage for different engineering applications of underwater impulsive sound sources. The charging energy storage part of the underwater plasma impulse sound source can also be designed according to the influence of the charging voltage on the impulse wave characteristics.