The microstructure and spectral properties of Er³⁺ doped transparent oxyfluoride glass ceramics with high fluorine content werereported. Two samples with the same initial contents(50SiO₂-45PbF₂-5PbO-1ErF₃) were prepared under the different preparation parameters. The final fluorine contents weredetected by a fluoride ion selective electrode. The results shows that the final fluorine contents increase by covering crucibles with corundumlid during melt. The samples were characterized by Xray diffraction, transmission electron microscopy(TEM), absorption spectra and upconversion luminescence spectra. The results show that PbF₂ crystals were precipitated in the sample with high fluorine content before heat treatment. And the PbF₂ crystals precipitated inside the glass matrix are spherical with diameters of approximately 10-15 nm in size from the high resolution TEM micrograph. The absorption spectra, J—O parameters and the upconversion spectra show that the Er³⁺ ions were located in crystal-line and vitreous mixed states. It is different from the sample with low fluorine content which is completely amor-phous. After heat treatment, Er³⁺ ions that remain in the glassy phase entered into fluoride nanocrystals in the sample with high fluorine content. The fluorine environment decreases non-radiative transfer which eases the upcon-version processes. Hence, the upconversion luminescence intensity of Er³⁺ ions in the high fluorine content sample after heat treatment is much stronger than that in the precursor sample.