The invention discloses a nut corner angle polishing device. The nut corner angle polishing device comprises a workbench. A three-direction polishing mechanism is arranged on the upper surface of the workbench. A clamping groove is machined in the upper surface of each support plate. A vertical rod is arranged on the upper surface of the workbench and located on one side of a set of sliding rails. A third vertical installing plate is arranged on the upper surface of the vertical rod. A controller is arranged on the front surface of the third vertical installing plate. A commercial power interface is arranged on the rear surface of the workbench. A supply terminal of the controller is connected with the commercial power interface through a wire. The output end of the controller is connected with an electric trolley, a second electric trolley, a linear motor, a hydraulic cylinder, an electric push rod, a third electric trolley, a second electric push rod, a rotation motor and a mini-type linear motor through wires. The nut corner angle polishing device has the beneficial effects that semiautomatic rotation and fixed polishing is achieved, the polishing speed is high, manpower is liberated, the work efficiency is improved, moving is convenient and fast, using is convenient and novelty is high.