Power chuck is a fixture used for clamping workpieces in the field of machining, including hollow power chuck and medium solid power chuck. There is a through-hole in the middle of the hollow power chuck. The matching power source, such as hydraulic cylinder, is also hollow. The workpiece can pass through the front end of the hollow power chuck, while the middle of the medium solid power chuck and its matching cylinder are solid, which are mainly used for processing disc workpieces. The medium solid power chuck is connected with the oil cylinder installed at the rear end of the machine tool shaft through a pull rod. In the process of workpiece cutting, the medium solid power chuck rotates at high speed together with the pull rod and power source and the main shaft of the machine. Due to the large volume, heavy mass and large inertia of the existing medium solid power chuck during high-speed operation, the load of the machine tool spindle is increased, resulting in poor operation stability of the machine tool spindle. In addition, the existing power chuck also has problems such as high friction on the mating surface, low mating accuracy, no dust-proof function, and inconvenient assembly.