The objective of this paper is to investigate the effect of shape and size of polishing pad on the material removal characteristics in the NC polishing. The material removal model was established based on Preston equation. The law of the effect of shape and size of polishing pad on the model was simulated. Experiments were carried out. Results showed that both of the shape and size of polishing pads influence the shape of material removal curves, polishing efficiency, and surface roughness. The amount of removed material increases with the increasing of size of polishing pad.