Ce3+ ions were doped into Si nanocrystals snc-Sid embedded in SiO2 matrix snc-Si/SiO2d by evaporation of CeF3 powder onto the surface of nc-Si/SiO2 and followed by thermal annealing in nitrogen ambient at different temperatures. Photoluminescence sPLd properties of the doped samples were studied. It has been found that the PL intensity of nc-Si can be remarkably enhanced and the enhancement depends on the doping concentration. Photoluminescence excitation spectra of the doped and undoped nc-Si imply that the enhancement comes from energy transfer from Ce3+ ions to nc-Si when excitation wavelength ranges from 240 to 320nm.