Abstract: Applying electromagnetic stirring technique to RH vacuum degassing system, how the gas bubbles move in the swirlings driven electromagnetically in the ascending pipe of RH system is investigated combining water modeling experiment with numerical simulation. Both the experiment and simulation results reveal that the gas bubbles are distributed in swirling field and bubbles' motional path presents spiral, and that the bubbles come together at the center of the pipe under the influence of swirlings. In addition, the swirlings prolong the staying time of non-metallic inclusions in RH system and then extend their motional paths, thus providing more chances for non-metallic inclusions to collide or combine with gas bubbles so as to benefit the removal of inclusions.