The work aims to prepare excellent CeO2 polishing agent. A kind of CeO2 nanoparticles polishing agent with excellent polishing properties was prepared by four kinds of dispersants of different concentrations. Its properties were tested by laser particle analyzer, UV-visible spectrophotometer, etc. Its characteristics in CMP of quartz glass sheet were investigated. The test results showed that different dispersing agents had different dispersing functions, and the concentrations of dispersant affected the dispersing results directly. Ionic dispersant achieved stable dispersion of polishing agent mainly by virtue of electrostatic stabilization and the non-ionic dispersant by steric hindrance. The dispersing stability of anionic dispersing (SDBS) and non-ionic dispersant (PVP) was obviously superior to that of the cationic dispersing agent (CTAB). And the dispersing stability of a mixture agent consisting of the anionic dispersant and nonionic dispersant was superior to that of single dispersant. CeO2 nanoparticles polishing agent prepared by mixed dispersing agent keeps uniform and stable dispersion after standing still for 72 hours, meeting the requirements for dispersion stability of polishing agent. When CeO2 nanoparticles polishing agent prepared by methods presented in this paper is used for CMP of quartze glass, the materials are mainly removed by absorption effect of CeO2 nanoparticles. The surface roughness Ra of polished surface is up to 10 nm without scratches and can improve the polishing quality of quartz glass efficiently.