To improve the fabricating quality of a SiC aspheric mirror, this paper researched the removal function in fixed abrasive technology involved in the mirror fabrication. The removal function was tested in the earlier round-pellet polishing pad, then a filling factor was introduced to evaluate the removal function obtained from the experiments and the relation between round-pellet pad structure and filling factor was established. To improve the filling factor and the characteristic of polishing pad, the pad structure was optimized according to the experimental results of the round-pellet pad .The removal function of the new polishing pad was simulated by MATLAB. A stability experiment in the full aperture was performed, and the both fixed abrasive and slurry abrasive polishing experiments were conducted under the same fabricating conditions. Finally, the Structural Similarity Index (SSI) was introduced to evaluate the similarity between simulations and experiments for the removal of large aperture mirror, and the best SSI of multi-square-pellet pad is 0.425 7. The comparison results are acceptable and positive, which shows that the optimized fixed abrasive polishing pad is highly promising for fabrication of large aperture SiC mirrors.