As an important raw material for synthesis of phosphor and laser gain medium, the sesquioxide of praseodymium (Pr2O3) receives few attentions due to its susceptibility to change of valence and hygroscopicity in air. In this study, thermal gravity-differential thermal analysis (TG-DTA), X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), Flourier transform infrared spectroscopy (FT-IR), ultraviolet-visible (UV-Vis) spectroscopy and fluorescence spectroscopy (FL) were employed to investigate the reduction process from Pr6O11 to Pr2O3 and corresponding mechanism in air and Ar/H2 atmosphere as well as the crystal phases, morphologies, particle sizes and valence states of the two kinds of oxides. Furthermore, the photoluminescent properties of praseodymium oxide were analyzed in relation to the valence state of praseodymium. The results show that the phase transition of Pr6O11 is significantly different in different atmospheres. The reduction of Pr6O11 is accelerated in Ar/H2 atmosphere and Pr2O3 can be obtained at 800 ℃. In addition to adsorption in ultraviolet region resulted from the transition from valence to conductive band, the Pr2O3 containing Pr 3+ also shows the absorption in visible light band caused by the f→f transition. Pr6O11 shows strong absorption to UV-Visible wavelengths over 320 nm, which is related to the charge transfer between the Pr 4+ and oxygen ion. The wide band in the fluorescence emission spectrum of Pr2O3 indicates that the lowest energy 第*期 顾军毅, 等: 还原制备 Pr2O3 粉体及其结构和光学性能研究 2