The invention discloses a giant magnetostrictive torsional vibration transducer. The giant magnetostrictive torsional vibration transducer comprises a shell, an output rod, a supporting plate, a plurality of giant magnetostrictive material pieces, a cooling water jacket, a coil framework, a drive coil and a cooling water pipe. An output hole is formed in the shell. An output flange with the central axis coinciding with the central axis of the output rod is arranged on the output rod. The output rod extends out of the shell through the output hole. The supporting plate is arranged in the shell and is spaced from the output flange in the axial direction of the output flange. The giant magnetostrictive material pieces are arranged between the output flange and the supporting plate in the circumferential direction of the output flange at equal intervals. The cooling water jacket is arranged in the shell and surrounds the giant magnetostrictive material pieces. The coil framework is arranged in the shell and surrounds the cooling water jacket. The drive coil is wound on the coil framework and the cooling water jacket. The cooling water pipe is connected to the cooling water jacket and extends out of the shell. The giant magnetostrictive torsional vibration transducer can output ultrasonic torsional vibration and has the advantages that the output power and the vibration amplitude are large and overheat is not prone to happening.