Fine spherical particle sized ceria (CeO2) was prepared by homogeneous precipitation method with ammonium bicarbonate as precipitant. The prepared CeO2 has the primary particle size of 10～50 nm when calcined between 400～700 ℃ analyzed by XRD and the aggregated particle size is about 300 nm measured by LASER particle sizer. SEM, TG-DTA and Zeta-potential analyzer were employed individually to study the morphology and the formation of CeO2 product. It was found that excess NH4NO3 can serve as an sphericallization agent to prepare spherical CeO2 powder by precipitation method.