A Ce3+-doped nanoscale SiO2 material was prepared by sol-gel method through adding Ce(NO3)3 and the samples were decorated by Cl- at different temperatures to study the effect of Cl- decoration on the luminescent properties of Ce3+ in SiO2. The components and luminescent properties of Ce3+ doped SiO2 after treatment were studied by X-ray photoelectron spectra, absorption pattern and fluorescence spectra. The measurement of luminescence showed that the Cl- decoration not only enhanced the intensity of the luminescence of Ce3+ doped SiO2 but also shifted the luminescent band to the short wavelength: the wavelength of emission shifted from 445 nm to 390 nm and the excitation from 326 nm to about 290 nm, and this shift was reversible. When the samples were retreated in the air after Cl- decoration, the intensity and wavelength of the photoluminescence resumed to the original value before Cl- decoration.