β-SiAlON-SiC composites were prepared using SiC particles and fines, silicon powder, AlN powder, α-Al2O3 micropowder and flake graphite as starting materials. The influence of the graphite (particle size of ≤45 and ≤300 μm, addition of 3.0%, 5.5%, 7.5%, and 10.0%, by mass) on the molten-alkali corrosion resistance was investigated. The results show that the molten alkali resistance for the β-SiAlON-SiC sample with 7.5% of graphite (≤300 μm) is optimal, showing the lowest mass change rate after corrosion and the highest retention ratios of cold modulus of rupture and hot modulus of rupture.