Al2O3-SiC-SiAlON composite specimens have been prepared using fused alumina, ultra fine α-Al2O3, Si and Al powders as starting materials and liquid phenol formaldehyde resin as binder and firing at 1 500 ℃ for 3 h in carbon embedded condition. Thermo-mechanical properties of Al2O3-SiC-SiAlON composites have been studied. The results show: (1) Al2O3-SiC-SiAlON composites can be prepared and sintered at 1 500 ℃ under carbon embedded condition. When Si/Al ratio is 8/0 and 7/1, the prepared composite is Al2O3-SiC-O’SiAlON; when Si/Al ratio is 5/3 and 3/5, the prepared composite is Al2O3-SiC-β-SiAlON. (2) The composites possess high temperature strength properties. Hot modulus of rupture at 1 400 ℃ is 10-30 MPa. They are in elastic range up to 1 000 ℃, after which plastic deformation is observed; even at 1 400 ℃, amount of deformation is relatively low. (3) The composites possess good thermal shock resistance, their residual strength ratio (ΔT=1 100 ℃) is 65%-80%. (4) The marked improvement in thermo-mechanical properties of Al2O3-SiC-SiAlON composites may be attributed to the in-situ formation of SiC, SiAlON and AlN, the fibrous SiC, columnar SiAlON and tabular-like AlN fill in the corundum skeleton structure creating strengthening and toughening effects.