The control of the motion of small gas bubbles by a vortex ring is explored through numerical simulation. Hydrogen bubbles with a diameter of 0.2 mm are arranged in quiescent water, forming a bubble cluster. A vortex ring is launched vertically, passing through the bubble cluster. The behaviors of the vortex ring and bubble motion are analyzed. The diameter of the vortex ring at launch is 42.5 mm, and the bubble volume fraction is less than 0.04. As the vortex ring convects through the bubble cluster, it displaces and entrains the bubbles. After the vortex ring passes through the cluster, the bubbles are involved in the vortex ring. The research also clarifies the evolution of the diameter and circulation of the vortex ring.