The present application provides a high-gravity device for generating nano/micron bubble and a reaction system. In the device, the liquid phase is continuous phase and the gas phase is dispersed phase. A gas enters the interior of the device from a hollow shaft, and the gas is subjected to primary shearing under a shearing effect of aerating micropores to form bubbles; then, the bubbles rapidly disengage from the surface of a rotating shaft under the effect of the rotating shaft rotating at a high speed, and are subjected to secondary shearing under the high-gravity environment with the strong shearing force formed by the rotating shaft to form nano/micron bubbles. The device has the advantages of fastness, stability, and small average particle size. The average particle size of the formed nano/micron bubbles is between 800 nanometers and 50 microns, and the average particle size of the bubbles can be regulated in a range by adjusting the rotating speed of the rotating shaft.