The invention relates to porous closed heat preservation ceramic and a preparing method thereof. The preparing method comprises the following steps that firstly, materials are drawn, wherein molybdenum tailings, float glass powder, alumina, borax, talc, pore forming material SiC powder and a triethanolamine grinding aid are drawn and ground, and are put into a trapezoid heat resistant steel die, laid flatly and compacted; secondly, molybdenum tailing heat preservation ceramic is sintered, and the low-density porous closed heat preservation ceramic finished product of an even bubble structure is obtained. The porous closed heat preservation ceramic and the preparing method thereof have the advantages that the production cost is reduced, environment protection is facilitated, and far-reaching significance is achieved on reduction of occupied land and environment protection by using the molybdenum tailings; a large amount of K2O is contained in the molybdenum tailings, the sintering temperature of the porous closed heat preservation ceramic can be easily reduced, and thus energy conservation and environmentally friendliness are achieved; the rich resources of pulverized coal and silicon carbide are selected as pore forming materials, the preparing technology of the porous closed heat preservation ceramic is simple, and industrialization production is facilitated.