In order to enhance performance of pre-cast shapes of alumina based castables, the present work explored the approach of forming in-situ bonding phases by incorporating Si powders and then heating in carbon embedded atmosphere. Using tabular alumina as aggregates, tabular alumina, SiC powders, Si powders, calcium aluminate cement, microsilica and ultrafine α-Al₂O₃ powders as matrix, alumina based ultra low cement (ULC) castables were prepared. Influences of Si powder addition at 0, 4%, 6%, 8% and 10% (in mass) on regular properties, cold modulus of rupture (CMOR), hot modulus of rupture (HMOR), thermal shock resistance (TSR) and microstructure of the castables after carbonization were investigated. After incorporation of Si powders and carbon embedded heating, the in-situ mullite and nonoxide phases such as SiAlON and SiC can be formed by oxidation, nitridation or carbonization reaction. HMOR and TSR of the castables with inª²situ nonoxides bonding are obviously improved. After carbon embedded heating, the HMOR at 1 400 ¡æ increases from 1.6 MPa  to 8.3 MPa, and the residual CMOR ratio after thermal shock increases from 64.9% to 137.9% when Si addition increases from 0 to 10%.