Abstract: The precursor of nano-sized Y₂O₃ was prepared by ammonium oxalate precipitation method，with Y₂O₃ and concentrated nitric acid as raw materials，with ammonium oxalate as precipitant，and hexadecyl trimethyl ammonium bromide as dispersant.Nano-sized Y₂O₃ particles were prepared by calcining the precursor in the air.The decomposition temperature of precursor was confirmed by DTA-TG.The product was characterized by XRD and SEM.The particle size distribution of the products prepared with different amount-of-substance ratios of reactants was measured by laser particle analyzer.Finally，the optimum preparation conditions of nano-sized Y₂O₃  were obtained.Under the optimum conditions，the nano-sized Y₂O₃  with average particle size of 40 nm could be prepared and the morphology was ellipsoidal.

Key words: nano-sized Y₂O₃, ammonium oxalate, precipitation method