Abstract: The densification behavior, phase composition, mechanical properties and microstructure of hot-pressed multi-phase β-Si₃N₄/α-Sialon ceramics were studied by XRD, mechanical measurements andSEM. The results indicated that the multi-phase β-Si₃N₄/α-Sialon ceramics mix the mechanical properties ofβ-Si₃N₄ and α-Sialon, the phase composition and mechanical properties can be tailored by adjusting the composition of start powders. Compared with a-Sialon ceramics, the strength and toughness of the multi-phase β-Si₃N₄/α-Sialon ceramics are increased by in-situ toughness because of adding the β-Si₃N₄ phase with a highaspect ratio.