Eu ions doped SiO2 thin films, SiO2(Eu), were prepared by co-sputtering of SiO2 and Eu2O3 and Eu ion implantation into thermally grown SiO2 films. The Eu-L3-edge X-ray absorption near edge structure (XANES) spectra of SiO2(Eu) films show a doublet absorption peak structure with energy difference of 7 eV, which indicates the conversion of Eu3+ to Eu2+ at-high annealing temperature in N2. The strong blue luminescence of SiO2(Eu) films prepared by ions implantation after films annealed above 1100 ℃ confirms the above argument.