Anti-permeation castable uses scientifically dense gradation, is compact in structure with low interconnected porosity, and provides excellent resistance to the permeation of molten media, effectively blocking the inward erosion of aluminum liquid, electrolyte and molten slag. It has good thermal stability and, being cast monolithically without joints, is used as an anti-permeation isolation layer for furnace bottoms and electrolytic cells, protecting the insulation layer and furnace body and extending kiln service life.