Corrosion resistance of four typical refractories against coal-water slurry coal slag, was investigated in laboratory. These typical refractories are high chromia brick (Cr2O3–Al2O3–ZrO2), fused AZS brick (Al2O3–ZrO2–SiO2), high zirconia brick (ZrO2) and Si3N4 bonded SiC brick, respectively. The cup test and micro-structural analysis method were used to evaluate the corrosion resistance and reaction mechanism at high temperature. Meanwhile, potential reactions between refractories and slag are predicted using thermodynamic calculation. The result shows that infiltrated depth increases in following order: Si3N4 bonded SiC brick < fused AZS brick < high zirconia brick < high chromia brick. The ZrO2 dissolution and higher porosity for the high chromia brick synergistically result in the worst corrosion resistance. Whereas, for the high zirconia brick, the continuous slag infiltration accelerate dissolution of ZrO2 grains, which decreases corrosion resistance. Due to the extremely low porosity, slag infiltration can be effectively hindered, and fused AZS brick has better slag corrosion resistance. For the Si3N4 bonded SiC brick, poor wettability, protective SiO2 film and increased slag viscosity synergistically contribute excellent corrosion resistance.