The invention discloses a method for preparing a heat-preservation shell powder coating material. The method comprises the following steps: (1) sufficiently mixing a dispersant, a wetting agent and water, sequentially adding nano titanium oxide, an ash calcium powder and a flame retardant, and uniformly stirring so as to obtain a mixture A; (2) uniformly mixing the mixture A with a shell powder soas to obtain a mixture B; (3) uniformly mixing the mixture B with methyl ethyoxyl silicon oil, nano bentonite and an argil powder so as to obtain a mixture C; (4) uniformly mixing the mixture C withan alumina silicate fiber so as to obtain a mixture D; (5) mixing and stirring a silicon acrylic emulsion with the mixture D so as to obtain a mixture E; (6) uniformly mixing the mixture E with a thermal-insulating composite packing and plant glue, and further uniformly mixing with functional aids, so as to obtain the heat-preservation shell powder coating material. By adopting the scheme of the invention, a stable viscous membrane can be prepared, and the material is good in heat-preservation and thermal insulating property, is green and healthy and has a wide market prospect.