Abstract: In view of the technical requirements for rapid and reliable automatic welding repairment of defects such as corrosion cracks in the dissolver for spent fuel reprocessing, a direct current added-high-frequency pulsedd tungsten inert gas arc welding method was developed in this paper, and a series of bead on plate welding experiments with 10 and 16 mm thick plate were performed. Taking the variations of arc-weld pool characteristic as the research object, the arc characteristic, and the flow behavior and the temperature field evolution of weld pool of pulsedd TIG with adding direct current and without were compared, respectively. The mechanism of increasing weld penetration was discussed. The results show that the high-frequency pulsed current makes the arc to produce electromagnetic contraction, and the compressed degree and the weld penetration positively correlates to the pulsed frequency (1 ~ 5 kHz); the reason of the penetration increase in the direct current added- high-frequency pulsed welding process is that the direct current added pulsed arc increases the arc current and energy density and rises the surface liquid metal temperature of weld pool, and increases the electromagnetic stirring force of the molten pool to improve the flow intensify of molten pool, sufficient convection heat exchange, and enhances the thermal inertia of the molten pool, finally. This method is able to reliably realize the one-sided welding and back formation of the butt joint of 5 mm thick stainless-steel plates.