Using commercial aluminum chloride and yttrium chloride as raw materials, YAG nanopowder was synthesized by using the co-precipitation method. YAG transparent ceramics were prepared through high-temperature vacuum sintering from the nanopowder. Thermogravimetry-differential thermal analysis (TG-DTA), Fourier transform infrared (FT-IR), X-ray diffraction (XRD) and other methods were used to study the effects and rules of chlorine salt concentration and dispersant PEG-6000 concentration on phase formation, particle size, and crystal grain size. With mixed solution of 0.25 mol·L^-1 AlCl₃·6H₂O and 0.15 mol·L^-1 YCl₃·6H₂O as the reactant, 1.0 mol·L^-1 NH₄HCO₃ as the precipitant, and 20 g·L^-1 PEG-6000 as the dispersant, the YAG powder obtained by calcining the precursor at 1100 ℃ for 6 h using the reverse titration coprecipitation method has optimal performance, with an average particle size of 66 nm. The resultant YAG ceramics had linear transmittances of 45.0%@400 nm and 52.8%@1100 nm (1 mm thickness), which need to be further optimized