The invention provides a coal-based solid waste foaming heat insulation material and a preparation method thereof. The coal-based solid waste foaming heat insulation material provided by the invention is prepared from a mixture of the following raw materials in parts by weight through foaming processing: 20 to 70 parts of silicon-calcium slag subjected to heat treatment, 5 to 40 parts of fly ash, 3 to 10 parts of desulfurized gypsum, 5 to 44 parts of slag powder, 3 to 15 parts of cement clinker and 0.2 to 3 parts of an additive. According to the coal-based solid waste foaming heat insulation material provided by the invention, coal-based solid wastes including the silicon-calcium slag, the fly ash, the desulfurized gypsum and the like can be absorbed on a large scale, and the prepared coal-based solid waste foaming heat insulation material has the properties of low density, high strength, low coefficient of thermal conductivity and the like, and meets standard requirements of a cement-based foam heat insulation board. The preparation method of the coal-based solid waste foaming heat insulation material, provided by the invention, is simple, molding and curing time is short, and the production efficiency is high.