The preparation of a well-dispersed, high solids content suspension is the foundation for colloidal forming methods to achieve ceramic green bodies with a uniformly microstructure, and meet the application requirements of various optical window materials. This article aims to enhance the dispersion stability of Y₂O₃ suspension by utilizing the synergistic effect of two dispersants, namely triammonium citrate (TAC) and ammonium polyacrylate (A40). The influence of the mixing ratio of two dispersants on the stability of Y₂O₃ suspension and the microstructure of formed green bodies were mainly investigated, and the advantages of the dual dispersant system in improving the solid content and stability of Y₂O₃ suspension were determined. The results show that the solid content of Y₂O₃ suspension could reach 38% (volume fraction) under the condition of TAC to A40 mass ratio of 7∶3. A uniformly microstructure and densely packed particle was achieved. Y₂O₃ transparent ceramics with a diameter of 9 mm and a thickness of 1 mm were obtained by vacuum sintering at 1 800 ℃, with a transmittance of 70.34% at 800 nm.