The nanocrystalline Gd 2 O 3 :Eu 3+ powders with cubic phase were prepared by a combustion method in the presence of urea and glycol. The effects of the annealing temperature on the crystallization and luminescence properties were studied. The results of XRD show pure phase can be obtained, the average crystallite size could be calculated as 7, 8, 15, and 23nm for the precursor and samples annealed at 600, 700 and 800°C, respectively, which coincided with the results from TEM images. The emission intensity, host absorption and charge transfer band intensity increased with increasing the temperature. The slightly broad emission peak at 610nm for smaller particles can be observed. The ratio of host absorption to O 2− –Eu 3+ charge transfer band of smaller nanoparticles is much stronger compared with that for larger nanoparticles, furthermore, the luminescence lifetimes of nanoparticles increased with increasing particles size. The effects of doping concentration of Eu 3+ on luminescence lifetimes and intensities were also discussed. The samples exhibited a higher quenching concentration of Eu 3+ , and luminescence lifetimes of nanoparticles are related to annealing temperature of samples and the doping concentration of Eu 3+ ions.