The invention discloses an automatic grinding fixture for a numerical-control machine tool, and relates to the technical field of auxiliary accessories for numerical-control machining. The automatic grinding fixture is provided with a mounting plate. A rotary cylinder is arranged on the mounting plate, a die clamping seat is arranged on the rotary cylinder, positioning dies are arranged on the die clamping seat, and workpiece embedding grooves are formed in the positioning dies; a reference positioning slide rail is arranged on the mounting plate, positioning sliders are arranged on the reference positioning slide rail, reference positioning blocks are arranged on the positioning sliders, reference positioning cylinders are arranged on the mounting plate, piston rods of the reference positioning cylinders are connected with the positioning sliders, detection yielding cylinders are arranged on the mounting plate, detection positioning cylinders are arranged on the detection yielding cylinders, displacement detection frames are arranged on piston rods of the detection positioning cylinders, and displacement detection devices are arranged on the displacement detection frames; pliers are arranged on the mounting plate and are positioned at the rear side of the die clamping seat, jaws of the pliers are positioned above the workpiece embedding grooves, a support frame is arranged on the mounting plate, pliers driving cylinders are arranged on the support frame, and piston rods of the pliers driving cylinders are hinged to handles of the pliers. The automatic grinding fixture has the advantages that the automatic grinding fixture is simple in structure, convenient to use and high in production efficiency, and the labor intensity can be relieved.