The invention provides a one-piece clamp used for the clamping and grinding of bearing inner and outer rings and belongs to the technical field of ceramic bearing processing. A thrust ball bearing is arranged in a first clamp body groove of a clamp body, an abrasive segment is arranged in a second clamp body groove, a bearing ring is arranged in the second clamp body groove, the outer side of the second clamp body groove of the clamp body is provided with a bolt clamping regulating device, the bolt clamping regulating device is connected with the abrasive segment and used for fixing and regulating the abrasive segment, one end of a flange ejector rod is of a disc structure and in contact with a bearing ring, and the end part of the other end of the ejector rod is provided with a connecting column. According to the clamp, by arranging the two clamp body grooves, placing the bearing ring in the clamp body grooves and arranging the arc-shaped abrasive segment at the outer part, the two side edges, perpendicular to the periphery, of the bearing ring are fixed through the thrust of the thrust ball bearing and the flange ejector rod, and the outer ring is ground; after the flange ejector rod is removed, the inner ring is directly ground; and therefore, the grinding of the inner and outer rings of cylindrical surfaces of the bearing ring is finished through one clamping, and the problem of coaxiality errors caused by two-time clamping is solved.