To provide nutritious and fresh processed foods, non-thermal food processing technologies have been developed in recent years. Among others, a non-thermal food processing method utilizing underwater shockwaves has cost-effectiveness. In this method, the design of a high voltage multiplier and its discharging method are key factors for processing target foods effectively. This paper proposes a non-thermal food processing system utilizing wire discharge of dual electrodes in underwater. Unlike conventional non-thermal food processing systems, the proposed system has two pairs of electrodes with thin metal wires. Owing to the electric discharge using thin metal wires, the energy to generate underwater shockwaves can be decreased. For this reason, by only one electric discharge, both sides of the target food are crushed by the proposed technique. The experiments using a laboratory prototype clarified that the proposed method can soften the whole flesh of the target food effectively. Furthermore, by assuming a four-terminal model, an equivalent model of the high voltage multiplier was analyzed theoretically. Concerning the series-connected voltage multiplier, the design conditions were derived to estimate the characteristics such as output voltage and power efficiency.