The invention discloses a slag, carbide slag and ceramsite high-strength wall thermal insulation material and a preparation method thereof. The high-strength wall thermal insulation material is prepared from slag powder, carbide slag powder, ceramsite, sand, calcium carbonate, latex powder, cellulose ether and water; the mass percent is 10.0 to 50.0% of slag powder, 8.0 to 40.0% of carbide slag powder, 30.0 to 60.0% of ceramsite, 15.0 to 30.0 % of sand, 5.0 to 20.0% of calcium carbonate, 1.5 to 5.0% of latex powder, 0.5 to 2.0% of cellulose ether and 12.0 to 30.0% of water. The high-strength wall thermal insulation material disclosed by the invention can improve an internal maintenance function of a cementing system; 28d compressive strength of the wall material can reach 25MPa, and the wall material is small in shrinkage; the slag and the carbide slag serve as the cementing system to replace cement, so that a novel path for resourceful utilization of carbide slag is provided, and high energy consumption required by producing cement is saved; the wall material has excellent thermal insulation performance, high strength, convenience to construction and no independent construction; the materials are wide in source and low in price; compared with a polyphenyl granule macromolecule thermal insulation material, the production cost of the wall material is low.