A porous material having a hierarchical pore structure, wherein a size and shape of interconnection parts of at least one level pore cavities is consistent with a size and shape of interconnection parts between the level pore cavities and the previous level pore cavities thereof, and an average value of equivalent diameters of the interconnection parts is larger than 45% of that of a diameter of small pore cavities of two adjacent pore cavities of the interconnection parts. The method for preparing the porous material includes: mixing a raw material powder with a pore-forming agent used for preparing the smallest level pores to formulate a slurry; uniformly filling the slurry into a polymeric material frame, and drying and crushing to form mixed grains; then uniformly mixing the mixed grains with the pore-forming agent used for preparing the upper-level pore cavities, forming a compact green body and sintering.