Abstract. YAG powders were synthesized by co-precipitation and two-step moderate calcinations at 600 / 800 °C or 600 / 900 °C in air, respectively. Two kinds of the synthesized powders both possess pure cubic YAG phases without any secondary phases such as YAH, YAP and YAM, etc.. The former has low agglomeration with nano-sized primary particles and large active energy, and the latter has homogeneously dispersed and well-crystallized particles, with a narrow particle size distribution of 8 -13 μm.