Abstract: Gasification of furfural residue with coal can realize its efficient and clean utilization. But the high alkali metal content in furfural slag is easy to cause the corrosion of gasifier refractory. Two gasification coals with different silica alumina ratio and a furfural residue were selected in the study. The effects of furfural residue additions on corrosion of silica brick, corundum brick, high alumina brick and mullite brick were investigated by using XRD, SEM-EDS and Factsage Software, and the corrosion mechanism was analyzed. With increasing furfural residue addition, the permeability of the slags to high-aluminium-bearing refractories first decreases and then increases, while the permeability on silica brick shows a slight decrease trend. Leucite (KAlSi₂O₆) with high-melting temperature is generated from the reaction of K₂O and SiO₂ in slag with Al₂O₃ in refractories after furfural residue is added, which hinders the infiltration of slag in refractories. Kaliophilite (KAlSiO₄) of low-melting point is formed when K₂O content increases, and this contributes to the infiltration of slag in refractories. The acid-base reaction between slag and silica brick is distinctly occurred, more slag reacts with SiO₂ in the silicon brick, resulting in a decrease in the amount of slag infiltrating into the silicon brick as furfural residue is added. The corrosion of silica brick is mainly caused by the acid-base reaction, while the corrosion of three alumina based refractory bricks of corundum, mullite and high alumina brick is determined by slag infiltration. A linear correlation between the percolation rate and slag viscosity is established, the slag permeability increases with decreasing viscosity, resulting in stronger permeability for the high Si/Al ratio slag with lower viscosity.