The invention provides a heat insulation material and a preparation method thereof. The heat insulation material comprises a cementing material, coarse aggregate, sand, water, vitrified microspheres, polypropylene fibers, an early strength agent, an accelerator and a water reducing agent, wherein the cementing material, coarse aggregate, sand, water, vitrified microspheres and polypropylene fibers account for the following mass parts: 320-430, 560-790, 560-790, 144-193, 60-140 and 0.5-0.9, and the early strength agent, accelerator and water reducing agent account for 3-6 percent, 2.5-4 percent and 0.5-1.2 percent of the mass of the cementing material respectively. The heat insulation material provided by the embodiment of the invention not only has physical mechanical properties of common mine supporting concrete as well as good heat insulation, simultaneously achieves the purposes of energy conservation, environmental protection and industrial waste utilization, meets the requirements of energy conservation and environmental protection, and has higher economic benefit.