Abstract Core/shell structured organic/inorganic composite microspheres has an important potential application in efficient and damage-free chemical mechanical planarization/polishing (CMP) as a kind of novel abrasive due to its uniform non-rigid mechanical property. However, the synergistic effect of material removal between organic cores and inorganic shells of composite abrasives is ambiguous. In this work, oxide-CMP performances of various slurries, containing polystyrene (PS) spheres, solid abrasives (SiO2 or CeO2), mixed abrasives ((PS+SiO2) or (PS+CeO2)), core/shell composites (PS/SiO2 or PS/CeO2), were investigated by atomic force microscopy. Experiment results indicated that the surfaces polished by composite abrasives exhibited lower surface roughness, fewer scratches as well as lower topographical variations than those by other type of abrasives. The core/shell structure of composite abrasives plays an important role in improving CMP behavior. Moreover, the organic cores are mainly beneficial to decrease surface roughness and mechanical damages, and the inorganic shells are in favor of improving material removal rate.