The luminescent properties of Eu3+:Y 2O 3 nanocrystals at low temperature were studied. Emission spectrum of Eu 3+ ions in Y 2O 3 nanocrystals with different size were compared. Based on excitation spectra at various temperatures, the relationship between the intensities of excitation spectra originating from different sites and the temperature has been analyzed. The luminescence decay curves of 5D 0- 7F 2 Eu 3+ (C 2) emission after excitation into the Eu 3+ (C 3i -C 2) pairs and isolated Eu 3+ ions were measured. The results show that the rate of energy transfer from Eu 3+ (C 3i ) to Eu 3+ (C 2) in the case of Eu 3+ (C 3i )-Eu 3+ (C 2) pairs is faster than that for the isolated Eu 3+ ions. The mechanism of quenching concentration increasing in Eu:Y 2O 3 nanocrystals has been discussed.