The invention belongs to the technical field of special optical fiber preparation, and relates to an optical fiber polisher preparing D-shaped optical fiber. A groove is formed at the edge of a fixture of the optical fiber polisher with a mechanical technology, and two screw holes are formed at the sides of the groove and a fixed plate, and used for fixing a quartz V groove. Bare fiber is fixed in the quartz V groove with optical fiber curing adhesive. In the grinding process, the D-shaped optical fiber is prepared through changing abrasive paper of different models and controlling the speed, grinding time and other parameters of the optical fiber polisher. According to the optical fiber polisher, the problems of complex process, high condition requirements and high cost for preparation of the D-shaped optical fiber are solved. With the method, the D-shaped optical fiber can be prepared easily, and other polishing methods are not required; the loss and cost are reduced, and technical processing can be performed on the surface of the D-shaped optical fiber directly; and convenient conditions are provided for fiber optical lasers and fiber optical sensors.