The invention relates to a porous insulating decorative material prepared by utilizing iron tailings and a preparation method thereof. The porous insulating decorative material is prepared by mixing and pelleting solid mixed powder and water and performing microwave sintering, and comprises a porous insulating layer and a glass surface decoration layer, wherein the porous insulating layer comprises the following raw materials in percent by mass: 75-85 percent of iron tailings powder, 2-10 percent of foaming agent, 0.1-1 percent of fluxing agent, 0.1-9 percent of foam stabilizer and 1-5 percent of wave-absorbing material; the glass surface decoration layer comprises the following raw materials in percent by mass: 45-75 percent of iron tailings powder, 20-50 percent of waste glass powder, 1-10 percent of thickening agent, 1-5 percent of expanding agent, 1-5 percent of color adjusting material and 1-3 percent of wave-absorbing material. The porous insulating decorative material has the beneficial effects that the defects of easy drop, complex process and the like caused by distribution and installation of the thermal insulation material and facing material are overcome; moreover, the utilization rate of the iron tailings is over 85 percent, and the emission reduction benefits are obvious.