Water pollution by synthetic dyes like methylene blue (MB) has significant environmental risks, and the conventional treatment methods often have some limitations. Advanced oxidation processes using plasma are effective including a high-voltage power source system. This study investigates a novel low-voltage pulsed submerged arc (SA) way. This work systematically analyzes the effects of several key electrical parameters—discharge frequency, voltage, and capacitance—on the degradation of a 10 mg·L⁻1 MB solution using the graphite electrodes. The results reveal that while higher frequencies or voltages increase the degradation rate, the increase of efficiency is non-linear. These diminishing returns are attributed to a decrease in energy conversion efficiency, where mass transfer limitations and radical self-recombination reactions become dominant at higher energy inputs.