Composite flame-retardant building insulation material and preparation method thereof

The invention relates to a composite flame-retardant building insulation material and a preparation method thereof. The composite flame-retardant building insulation material comprises ordinary Portland cement 425, fly ash grade II, silica fume, gypsum, bentonite, epoxy-modified hybrid emulsion, fiber, cellulose ether, a water repellent, LEE monomeric fire retardant, expanding agent, polyphenyl granule and a silane coupling agent KH550. The insulation material provided by the invention has the advantages of a low heat conduction coefficient, non-combustibility, water resistance, light weight, high mechanical strength and applicability to insulation of building walls.