In this work, the effect of microsilica addition on properties of mullite-corundum ceramic specimens fired at temperatures from 1550℃ to 1700℃ has been investigated. It is found that the temperature at 1650℃is an important turning point for the sintering of mullite-corundum ceramic. When the firing temperature excesses 1650℃, the mullite phase will decompose, which affects the properties and microstructure of the ceramic. The bulk density of the ceramic decreases with the microsilica addition, but increases with the firing temperature from 1550℃ up to 1700℃. The cold compressive strength of the specimens increases with firing temperature. Thermal shock resistance of the ceramic is strongly dependent of firing temperature, but little of the chosen microsilica addition.