The invention discloses a fireproof heat insulation building material and a preparation method thereof. The fireproof heat insulation building material comprises, by weight, 20-30 parts of expanded perlite, 9-15 parts of blast furnace slag, 15-20 parts of clay, 3-10 parts of dolomite powder, 5-18 parts of rubber, 7-18 parts of plant fiber powder, 4-10 parts of aluminum silicate fiber cotton, 10-17 parts of flame retardants, 2-15 parts of color master batches and 2-13 parts of auxiliary raw materials. The fireproof heat insulation building material has good effects of insulating heat and retarding flame, fire resistance of the building material is improved, energy storing and temperature adjusting functions of the material are achieved, indoor heat loss is prevented, and the heat insulation material takes the expanded perlite as a main raw material, so that the heat insulation material has the advantages that the material is light in apparent density, low in heat conductivity coefficient, good in chemical stability and free from toxicity and taste. The flame retardants of the building material are tetrabromobisphenol A which is one of flame retardant products subjected to the most scientific tests on the market and with the highest cost advantages.