The types of surface scratches on the fused-silica workpiece during the polishing process and the length of the scratches caused by impurity particles having different particle sizes in the ending stage are analyzed by introducing α-AL₂O₃ particles into the polishing process of fused-silica glass. Further, the effects of the polishing-powder mass fraction in the polishing solution and the polishing pad structure on the polishing quality of the fused-silica glass are studied. Results show that the impurity particles require sufficient support force provided by the polishing pad to produce scratches on the surface of the workpiece; the support force of the polishing pad on which the impurity particles are subjected depends on their positional height and the number of matrix particles participating in the polishing process. It is difficult to control the positional height of the impurity particles; however, at a relatively high polishing-powder mass fraction of 6%, the microporous pitch-polishing pad effectively reduces the scratching probability without introducing surface roughness or excessively affecting the polishing efficiency under identical process conditions. These observations exhibit guiding significance for processing and production.