Tetragonal phase BaTiO 3 :Eu nanocrystals were successfully synthesized using a hydrothermal method and a subsequent calcination treatment. The structures and morphologies of nanocrystals were characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and scanning electron microscopy. The photoluminescence properties of BaTiO 3 :Eu were investigated in detail. Under 398nm excitation, the emissions from Eu 2+ and Eu 3+ ions were observed, indicating that Eu 2+ and Eu 3+ ions coexisted in BaTiO 3 :Eu nanocrystals. Especially, the emission band of Eu 2+ from BaTiO 3 :Eu was observed to broaden with increasing Eu concentration. When the Eu concentration was 0.5mol%, the 5 D 0 → 7 F 0 and 5 D 1 → 7 F 0 emissions were observed. In addition, under 537nm excitation, the emission intensity increased with increasing Eu concentration.