Continuous polishing is the preferred method for processing large-aperture planar optical materials, especially playing an important role in ultra-precision processing of optics. The surface accuracy of components is directly affected by the surface shape of the polishing pad. To study the removal characteristics of polishing-pad surface materials with small-tools, accurately measuring the surface shape of the polishing pad is necessary. In this paper, the height of spiral sample points on the surface of a polishing pad is collected by laser displacement sensor, and the experimental detection errors are analyzed and calibrated. Subsequently, the actual shape of the polishing pad surface is calculated. Using a computer controlled polishing method for reference, the material-removal model of the polishing pad with tool correction is established, the material removal function of the pad in the correction range of the small-tool is simulated and calculated, and the material-removal characteristics of the polishing pad are analyzed. Finally, the correctness of the simulation results is verified with a small-tool correction experiment, which provides a theoretical basis for shape modification of the polishing pad.