YAG crystal possesses chemical stability, mechanical intension, thermal conductivity and isotropy. These properties make it widely be used as functional and structural materials. YAG powder was successfully synthesized by gel solid-state reaction. AlOOH were reacted respectively with Y2(C2O4)3•10H2O (Route YІ) and Y2O3 (Route YІІ). The XRD indicated that the main phases were from YAM to YAP, finally to YAG with the increase of temperature in both routes, and YAG began to generate at 1250°C. The single-phase YAG generated after holding for 4h at 1450°Cin the YІ, but a little bit of YAP and Al2O3 was still remained in the YІІ. It was that Y2(C2O4)3•10H2O might be decomposed into high-activity, loose-structure yttrium oxide, which promoted the diffusion of Al3+ ion. According to XRD analysis, YAG generated slowly during 1250°C~1300°C and then fast during 1300°C~1450°C. The SEM images showed that the primary particles of YІ were 2-3µm, larger than that of YІІ. Particle distribution indicated that the average diameter is 18.68μm in the YІ and 9.35μm in the YІІ.