The effects of Al2O3 on micro-structure and crystallization of oxyfluoride glass are investigated by infrared spectra, Raman spectra and X-ray diffraction analyses. The results show that AlO4 is connected with SiO4 units by means of angle connection, thereby forming the basic network of glass. When the content of Al2O3 increases, the structures of monomer and dimer increase in oxide glass matrix. Under the condition, the size of nanocrystals has a minimum value, while the structure of nancrystals is not affected.