Nano-scale powders of YAG(Y3Al5O12):Ce3+ were obtained by the polyacrylamide gel method. Furthermore, the crystal structures and spectra of these powders were studied. Compared with micro-scale powders obtained from co-precipitation process, nano-scale powders show decrease of lattice parameter. At the same time, the phenomena in the emission spectrum and excitation spectrum of nano-scale YAG:Ce3+ were found. The blue-shift peaks in both of the emission spectrum and the excitation spectrum are due to the transition between 5d-4f energy levels. It show that the structural characteristics of nanoscale YAG:Ce3+ influence the wavelength of spectra.