The effects of metallic cation concentration and dispersant on the crystal phase of Nd:YAG powders were studied. The powders were prepared by co-precipitation with ammonium hydration carbonate as precipitator. The crystal phase of Y2O3

YAM was observed at 0.16 mol·L-1 and 0.32 mol·L-1 of the metallic cation concentration. The solution with pH 8.0 and 0.08 mol·L-1 metallic cation concentration was suitable for the preparation of the Nd:YAG nanopowders. A small amount of sulfate ions dispersant influenced the dispersion and the phase transformation of the precursor during the calcining process. Nd:YAG transparent ceramic with high in-line transmittance was obtained by sintering the green body prepared by co-precipitation powder. 1.6 W laser output at 1064 nm was obtained with a 6 W pump power.