The invention belongs to the technical field of waste rubber treatment, in particular to a method for regenerating rubber powder by using supercritical carbon dioxide. The method comprises the following steps: enabling the supercritical carbon dioxide in a carbon dioxide tank to pass through a heat exchanger and reach the interior of a buffer tank; enabling the carbon dioxide to enter a supercritical reaction still containing waste rubber powder of 40 to 80 meshes and water accounting for 1/5 to 1/3 of the amount of the waste rubber powder, and continuously stirring in a saturation process; relieving pressure through a nozzle of the supercritical reaction still, and meanwile continuously supplementing pressure to the supercritical reaction still by the buffer tank, and after the rubber powder in the supercritical reaction still is wholly discharged, relieving pressure in the supercritical reaction still; drying the rubber powder in a storage tank, then putting into a single screw extruder, and extruding for further regenerating, thus obtaining regenerated rubber powder. Accoring to the method, the supercritical carbon dioxide is completely utilized to soften and swell the waste rubber powder, other ingredients such as a desulfurizer and plasticizing oil are not contained, and the environmental requirements on rubber powder and the environmental requirements in technical production are met.