This work investigated the thermo gravimetric (TG) change and explosion resistance of ultra　low cement Al2O3-SiO2 castables added with 0, 5%, 10%, 15% and 20% of ≤74 μm raw bauxite powders containing 72.8% Al2O3, respectively. The castables were prepared using white fused alumina as aggregate, powders of white fused alumina, fused mullite, α-Al2O3 ultrafines, 3% CA cement and 5% microsilica as the matrix portion. TG change of the castables was investigated by a thermo gravimetric analyzer for large size specimen. When the raw bauxite addition is less than 10%, the mass losing behavior of the castables is similar to that without raw bauxite, tending to reach a constant mass around 400 ℃, before which the mass loss is mild and producing little destructive influence. With more than 10% raw bauxite addition, however, the mass loss increases significantly, and the temperature to reach a constant mass increases to 600 ℃ or higher, unfavorable to structural stabilization. With the raw bauxite addition up to 20%, no negative influence on explosion resistance is found.