Dislocation defects induced by neutron irradiation can degrade the mechanical properties of reactor pressure vessel steel; although the properties can be restored by annealing, this treatment is energy- and time-intensive. A fast and energy-efficient method of decreasing the dislocation density is urgently needed. In this study, electric pulse treatment was applied to damaged A508-3 steel to remove the dislocation defects quickly. The pulsed electric current reduced the dislocation density in a brittle sample and improved the impact toughness. After electric pulse treatment, the ductile–brittle transition temperature was 11.8°C lower. Calculations revealed that the higher temperature around the dislocations and the electron wind force under the electric field decreased the activation energy of dislocation motion, causing the dislocations to move more easily. The dislocation defects can be annihilated as they move, decreasing the dislocation density.