Abstract: With the mullite sols prepared by coprecipitation method as a binder, the corundum castable was sintered at different temperatures (1 100,1 300,1 500℃). The effects of addition amount of mullite sols on the phase composition, sintering performance, compressive strength at ambient temperature and microstructure of the corundum castables were studied. The results show that with the increase of mullite sols addition amount, the bulk density of the sample first increased and then decreased; the apparent porosity first decreased and then increased. The phase composition of the sample mainly consisted of corundum phase and mullite phase. With the increase of sintering temperature and addition amount of mullite sols, the content of mullite phase increased; the compressive strength at ambient temperature of the sample was improved. When the mass fraction of mullite sols was 3%, the compressive strength at ambient temperature of the sample sintered at 1 500℃ was the largest.