Abstract: By super intensity pulse current generator of ZL-2, mechanical performance of 45 steel welded joint was strengthered by electromagnetic heat effect;By use of PC-control universal tester, the tensile strength was tested to compare the mechanical performance before and after pulsed current discharge;And SEM was adopted to analyse the fracture transformation before and after strengthening by using of electromagnetic heating. Results indicate that, because of the current detouring concentration effect in the welded joint when an appropriate pulsed current is switched on, super speed impulse quencher happens near the heat affected zone and white-bright structure forms, which improves the toughness and the mechanical performance of welded joint.For the jointed component, tensile strength increases more than 10% after pulse current discharge.