Al₂O₃-MgO castables have been widely used for working linings of steel ladle due to their superior hot strength and corrosion resistance. In this work, effects of microsilica, ultrafine alumina and MgO fines additions on the rheological behavior of the castables were investigated by means of IBB rheometer V1.0 to measure torque (shear stress) under varying shear rates. The results show that rheological properties of castables at varying shear rates are significantly improved with increase of microsilica additions (from 1 mass% to 5 mass%) and corresponding decrease in water addition; there is only little change in rheological behavior with variation of ultrafine alumina and MgO fines additions. Optimum ultrafine alumina and microsilica additions are recommended for castables with good rheological behavior.