Nano-sized Er3+∶Y3Al5O12 powders was successfully prepared via a simple sol-gel route at as low a temperature at 800 ℃ whereas a temperature much higher is necessary to obtain this compound by solid state synthesis (about 1500 ℃). The phase purity, composition and microstructural features of the materials were analyzed by means of X-ray diffraction(XRD), infrared spectroscopy(IR) and transmission electron microscopy(TEM), and no other intermediate phase were observed to form in the range of 700～1000 ℃. The luminescence spectra of Er3+ substituted for Y3+ in YAG in 1% content was characterized on samples at different temperature.