With the development of semiconductor industry, the chemical mechanical polishing technology has already became the main stream method of realize the surface global flatness. In order to understanding physical essence underlying this technology, the author carried out nanometer polishing experiment of silicon wafer using molecular dynamics (MD) simulation method. The simulation result shows that larger slurry grain generate much more vacancy, dislocation, larger residual stress and intensive plastic deformation than that of small one although the larger grain acquire better surface quality. (C) 2007 Elsevier B.V. All rights reserved.