Composing rare earth nitrates, polyvinyl alcohol (PVA) or polyacrylamide (PAM), urea and ammonia solution, the multicomponent hybrid precursors have been in situ assembled, where organic polymers (PVA or PAM) are used both as dispersing media and fuel. Then nanometer CeO 2 phosphors have been prepared with the thermalysis and X-ray diffraction and scanning electronic microscope (SEM) show that these materials have the nanometer size of 40–100 nm. The strong ultraviolet absorption properties of nanometer CeO 2 were studied firstly with excitation spectra and the results show that nanometer CeO 2 exhibit broad absorption band at the long wavelength ultraviolet region of 300–450 nm. It is found that different dopant rare earth ions (Eu 3+, Tb 3+, Sm 3+, and Dy 3+, doping concentration=1 mol%) can influence the ultraviolet absorption property of nanometer CeO 2. With increasing temperature of thermolysis, the ultraviolet absorption intensities increase.