Y2O3 powders were synthesized by adopting four different agitators during co-precipitation. The effect of the homogeneity of co-precipitation reaction process under different agitators on the phase compositions and morphology of precursors and Y2O3 powders were studied. Crystalline phase precursors were prepared from the 2-straight-blade turbine impeller and the 4-straight-blade turbine impeller, identified as (NH4)aY(OH)b(CO3)c·H2O. However, amorphous phase of Y(CO3)(OH)·nH2O (n = 1–1.5) were found from the 3-blade propeller type impeller and the 4-pitched-blade turbine impeller. The results showed that a better uniform mixture without layered and local circulations could be produced by the 4-pitched-blade turbine impeller. The prepared Y2O3 powders exhibited a high dispersibility, weak agglomeration and less sintering neck. This study was the first attempt to improve the co-precipitation reaction homogeneity to enhance the dispersion of powders, which was benefit to the controllable and repeatable synthesis of Y2O3 powders.