In order to prolong the service life of castables for hot blast stove pipes, effects of SiO2 micropowder addition and aggregate kind on properties of castables for hot blast stove pipes, and properties of silica sol bonded castables were researched using homogenized bauxite, andalusite particles, andalusite fines, white fused corundum fines, ᪲Al2O3 micropowder, pure calcium aluminate cement, SiO2 micropowder, and silica sol as starting materials. The results show that: (1) as SiO2 micropowder addition increases, the shrinkage rate of fired specimens increases; BD increases firstly, reaches the highest at 4 mass%, and then decreases; CMOR and CCS of all specimens increase gradually; so the appropriate SiO2 micropowder addition is 4 mass%; (2) the specimens with bauxite aggregate have better CCS and volume stability, but specimens with andalusite aggregate have better thermal shock resistance; (3) for castables for hot blast stoves using silica sol as binder, the addition of pure calcium aluminate cement can decrease the linear change rate after treatment at 1 400 ¡æ and can slightly enhance CCS and CMOR, but has very little influence on AP and BD; and the introduction of citric acid worsens the thermal shock resistance of specimens.