The present invention discloses a building composite material processed by using waste textile products, and belongs to the field of building materials, wherein the building composite material comprises the following raw materials by weight: 30-50 parts of waste textile products, 10-20 parts of diatomaceous earth, 5-10 parts of titanium gypsum, 15-18 parts of an aqueous polyester resin, 10-14 parts of an epoxy resin, 1-3 parts of glass fiber, 1-3 parts of nanometer silica, 2-6 parts of sodium hydrogen carbonate, 1-3 parts of a titanate coupling agent, and 2-4 parts of mineral oil. According to the present invention, the waste textile fibers are reasonably used to turn the waste into treasure so as to reduce the manufacturing cost, reduce the environmental protection pressure, and achieve the comprehensive utilization of the resources; the process is simple, the raw material source is wide, and the energy source consumption during the production process is low; and the prepared plate has characteristics of light weight, sound insulation, heat insulation, water resistance, fire resistance, good toughness, high fracture strength, and the like.