The almost monodisperse ellipsoid-like CeO2 nanostructures with rugged surface and many pores have been synthesized by a smart hydrothermal technique. Various techniques have been applied to investigate the CeO2 nanostructures, including XRD, SEM, XPS, Raman scattering, UV-vis and Photoluminescence (PL) spectra. The results showed that the ellipsoid-like CeO2 have a fluorite cubic structure and there are Ce3+ ions and oxygen vacancies existing in surface of samples. It is also found that there is a red-shifting in the band gap of the materials compared to bulk one, which is mainly attributed to the influences of the Ce3+ ions, oxygen vacancies and the morphology of the materials. The photoluminescence measurement indicated that the ellipsoid-like CeO2 samples exhibit excellent optical properties at room temperature, which can be reasonably explained for the influences of the concentration of oxygen vacancies and Ce3+ ions.