The invention relates to a high doped blast furnace heavy slag composite sand-based water-permeable brick and a preparation method thereof. The water-permeable brick is composed of a water-permeable surface layer and a water-permeable base layer. The water-permeable surface layer comprises, by mass, 150 to 200 parts of super-fine sand of heavy slag, 7 to 14 parts of epoxy resin, 2 to 4 parts of a curing agent, 0.02 to 0.4 parts of a hardening accelerator, 0.1 to 0.3 parts of a silane coupling agent and 0.02 to 0.1 parts of colorant paste. The water-permeable base layer comprises, by mass, 190 to 450 parts of ordinary Portland cement, 14 to 200 parts of sulphoaluminate cement, 1250 to 1650 parts of heavy slag, 0.1 to 0.6 parts of a water reducing agent and 90 to 160 parts of water. The high doped blast furnace heavy slag composite sand-based water-permeable brick utilizes a large amount of industrial waste blast furnace heavy slag, modified epoxy resin glue and a compound cementitious system, and has high interlaminar bonding strength, short hardening time, wear resistance and long service time.