The Al2O3-mullite system porous refractories were fabricated, and then pretreated by sol-gel. The samples were sintered at 1200°C for 3 hours. The microstructures and phases of the samples were analyzed by SEM and XRD respectively. The physical properties of the samples were measured according to National Standard of Refractory. Mullite-whiskers were formed in the pores of the samples. The pretreated samples were more permeable, and were greatly strengthened.