The invention provides a dampproof heat insulation material and a preparation method thereof. The formula of the dampproof heat insulation material comprises the following raw materials: heat return materials, fly ash bleaching beads, waste glass, ceramic powder, fly ash, foaming agents, cosolvents, antimonous oxide, zinc oxide, vesuvianite, diatom ooze and mineral wool cellulose. The method comprises the following steps of weighing raw materials according to the proportion; performing mixing; grinding the mixed raw materials; performing winnowing after the grinding; after a releasing agent coating onto the inner wall of a mold, putting the mixed material prepared in the first step into the mold; performing sealing; sequentially putting the mold and the first raw material into a sinteringfurnace for sequential preheating, softening treatment, foaming treatment and annealing treatment to prepare the dampproof heat insulation material. The heat insulation material provided by the invention can effectively achieve the dampproof effects; water vapor cannot be easily condensed onto the surface of the heat insulation material; the corrosion speed of the heat insulation material is decelerated, so that the service life of the heat insulation pipe is prolonged. In addition, the advantage of low cost is also realized.