Three-jaw chuck

The utility model discloses a three-jaw chuck which comprises a chuck body and clamping jaws. A reference plate is arranged on the end surface of the chuck body and provided with bayonets matched with the clamping jaws, and the thickness of the reference plate is less than the outwardly-extending distance of each clamping jaw in the axial direction of the chuck body. The three-jaw chuck has the advantages that the reference plate is provided with a reference surface, so that the center of a columned workpiece or a cylindrical workpiece and the center of a rotating shaft of a lathe are positioned on a same line; the problem that the columned workpiece or the cylindrical workpiece is required to be referenced when being clamped at each time is solved, so that the processing efficiency of the columned workpiece or the cylindrical workpiece is greatly improved; and meanwhile, the reference plate has a simple structure, is lower in production cost and is low cost, and is easy for large-scale popularization and app