Y2 O3 :Ti3 + powders were prepared by coprecipitation method at different temperatures in different sintering atmospheres. XRD spectra, excitation and emission spectra of Y2 O3 :Ti3 + powders were measured, and their morphologies were observed. Under the excitation of UV light, Y2 O3 :Ti3 + microcrystalline has a strong emission band near 439nm, and Y2 O3 :Ti3 + nanocrystalline has a more stronger emission band in the range of 400～500 nm. The fluorescence of Y2 O3 :Ti3 + nanopowder becomes strong observably as the grain size reduces, and the fluorescence covers whole visible light region. This indicates that Y2 O3 :Ti3 + nanopowder is expected to become a new generation light conversion phosphor for white LED or mercury lamp.