CeO2-coated Polystyrene (CeO2/PS) and SiO2-coated Polystyrene (SiO2/PS) composite particles were synthesized by chemical precipitation method. The as-synthesized composite particles samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), field emission scanning electron microscope (FESEM), thermogravimetric analysis (TGA) and Zeta potential measurement. The oxide chemical mechanical polishing (CMP) performance of the as-papered composite particles was studied by atomic force microscope (AFM). The results indicated that CeO2/PS composite particles had core-shell morphology and PS particles were uniformly coated by fluorite-structured CeO2. The Strawberry-shaped SiO2/PS composite particles were obtained, which particle size is about 200-300 nm. Surface roughness (RMS) within 5 μm×5 μm area of thermal oxide film surface after polished by CeO2/PS and SiO2/PS composite particles was decreased to 0.227 nm and 0.222 nm, respectively.