Eu doped Y2O3 and some kinds of other rare earth oxides nanoparticles such as Er2O3, Nd2O3, Ho2O3, Lu2O3, and Dy2O3 were prepared by a simple co-precipitation-solvothermal treatment-calcination process, where the co-precipitated amorphous hydroxide precursors obtained by adding rare earth nitrate solutions in ammonia solutions were heated in solvents such as water, alcohols and glycols, followed by calcination in air. The morphology of rare earth oxide particles strongly depended on the solvothermal reaction medium but not related to the kind of rare earth oxide. The powders prepared in water and ethanol possessed nanowire structure, where the aspect ratio of powder treated in water was higher than that in ethanol. The powders prepared by co-precipition-solvothermal treatment-calcination process using ethylene glycol consisted of near-spherical nanoparticles whereas that prepared by conventional co-precipitation-calcination method consisted of hardly agglomerated submicron particles. The nanoparticles of Eu3+ doped Y2O3 prepared by co-precipition-solvothermal treatment-calcination process showed similar intensity of photoluminescence with the submicron particles by co-precipition-calcination process.