The invention discloses an environment-friendly building brick and a preparation method thereof. The environment-friendly building brick is prepared from the following raw materials in parts by weight: 60 to 80 parts of construction waste, 10 to 18 parts of coal ash, 15 to 30 parts of mineral residue, 3 to 10 parts of marble, 1 to 2 parts of magnet, 1 to 3 parts of medical stone, 3 to 7 parts of fluorite, 1 to 2 parts of alundum powder, 15 to 30 parts of clay, 0.1 to 0.5 part of shell active carbon, 0.1 to 0.3 part of nanoscale aluminum oxide, 0.08 to 0.12 part of sodium rosinate, 0.05 to 0.1part of sodium tripolyphosphate, and 10 to 15 parts of water. The building brick has the advantages of high strength, good wear resistance, acid and alkali corrosion resistance, high compactness and the like, also has insecticidal and healthcare functions, and has a good visual effect.