The Ce3+ -doped Y2O3-Al2O3-SiO2 (YAS) bulk glasses with low SiO2 (<= 40 mol%) were prepared by flame spray-quench method and hot press sintering. YAG nanoglass-ceramics were derived from YAS bulk glass by a controlled crystallization. The differential thermal analysis (DTA) results showed that the glass-forming ability of YAS system was strongly dependent on SiO2 content and the supercooling degree required for forming YAS glass increased with the decrease of SiO2 content. The YAS glass compositions had been extended to low SiO2 phase region (10-40 mol%) by flame spray-quench method. The study of crystallization process showed that glass matrixes experienced initially a phase-separation followed by crystallization during the heat treatment. The phase-separated grains (100-300 nm) that were composed of YAG nanocrystallites precipitated in the glass matrix. And the intensity of emission spectra increased with the decreasing SiO2 content.