The invention discloses a glazed hollow bead-fly ash based fireproof heat insulation material and its preparation method. The fireproof heat insulation material is composed of glazed hollow beads, a mineral raw material, toughened fibers, an alkaline exciting agent, a waterproof agent and a water reducing agent. The mineral raw material comprises 70-100wt.% of fly ash, and also contains one of mineral slag, steel slag, silica fume, metakaolin, circulating fluidized bed ash bottom ash, red mud, and acid leaching residue of asbestos tailing; the glass beads account for 50-150wt.% of the mass of the mineral raw material; the toughened fibers account for0.1-1wt.% of the mass of the mineral raw material; the alkaline exciting agent accounts for 40-55wt.% of the mass of the mineral raw material; the waterproof agent accounts for 1-3wt.% of the total mass of the mineral raw materials and the glass beads; and water reducing agent accounts for 1-3wt.% of the total mass of the mineral raw materials and the glass beads. The preparation method comprises the following steps: fully mixing and stirring all the above raw materials, carrying out casting molding, and steaming at 50-90DEG C for 1-24h. The volume weight, the compressive strength and the heat conduction coefficient of the fireproof heat insulation material are 400-800kg/m<3>, 2.0-10.0MPa and 0.08-0.20W/(m.K) respectively. The fireproof heat insulation material can be used as a fireproof material, a heat insulation material and a sound insulation material.