Abstract: Disclosed is a system for reducing blade tip vortex cavitation by controlling mass flow. The system reduces blade tip vortex cavitation that occurs around blades of a propulsive propeller of a ship when the propulsive propeller rotates to generate force required to propel the ship across the sea by forming a plurality of flow holes in the propeller blades and controlling mass flow through the plurality of flow holes, i.e., appropriately discharging water to the outside or suctioning outside water through the plurality of flow holes, thereby reducing underwater noise and vibration of the hull. The system includes a propeller, a water feeding pipe, a water supply/suction unit, and a controller.