Abstract: The strain energy density is studied theoretically during pulse current discharging in a metal component with a circular embedding crack. The theoretical formula for temperature field, the thermal stress and strain energy densities are obtained for an open type crack based on a heat transfer formula, theories of unsteady thermal stress and the Hankel transform formula during pulse current discharging in a metal component with a disc-shaped sheet embedding crack. The formula obtained shows that a thermal stress field is formed at the crack tip during pulse current discharging, the thermal stress do negative work which reduces the component damage under tensile stress and the strain energy density is reduced after pulse discharging. Also, the difference of strain energy before and after pulse discharge is studied for Cr12MoV die steel with a disc-shaped sheet embedding crack under different tensile stresses. The study provides a theoretic basis for the applications of crack arresting with electromagnetic heating.