The invention relates to a closed-pore bauxite based mullite material and a preparing method thereof. According to the technical scheme, by mass, 40-95wt% of bauxite rawore powder and 5-60wt% of silicon dioxide material are mixed uniformly, an additive accounting for 3-10wt% of the raw material mass is added externally and stirred uniformly to obtain a mixture, the mixture is poured into a mold and formed under the pressure of 80-150 MPa to obtain a blank, and the blank is fired for 2-12 h at the temperature of 80-160 DEG C, then put into a high-temperature furnace and calcined for 3-18 h at the temperature of 1450-1750 DEG C in the high-temperature furnace to obtain the closed-pore bauxite based mullite material. The preparing method is low in production cost and saves resources and energy, and the obtained closed-pore bauxite based mullite material is high in closed porosity, small in volume density and large in compression strength.