The effect of Y₂O₃ addition on the sintering properties and microstructure of spinel was investigated using alumina-rich spinel as the raw material. The phase constitution and microstructure of the specimens were characterized by XRD and SEM, and the pore structure of the specimens was measured by a mercury porosimeter. The results indicate that a viscous melt forms wrapping around spinel crystals by adding a little Y₂O₃ powders (1 mass%), yttrium alumina garnet will crystallize around spinel crystals by adding more Y₂O₃ powders (≥3 mass%); the sintering properties of the spinel are significantly improved by adding Y₂O₃ powders less than 3 mass%, while they will be relatively weakened by adding Y₂O₃ powders more than 3 mass%.