Porous material and preparation method thereof

A porous material, comprising a material body, wherein the material body comprises pore cavities graded by pore size of the material and cavity walls surrounding the pore cavities, and lower-level pore cavities are arranged on cavity walls of upper-level pore cavities formed by surrounding a three-dimensional space;

• wherein pore cavities of same level are interconnected with each other, and pore cavities of different levels are also interconnected with each other, wherein the porous material has a tertiary pore structure, the third-level pore cavities have an average pore size of 230-410 nm, the second-level pore cavities have an average pore size of 135-140 μm, and the first-level pore cavity has an average pore size of 620-680 μm;
• and a size and shape of interconnection parts between the second-level pore cavities is consistent with a size and shape of interconnection parts between the second-level pore cavities and the first-level pore cavities, and an average value of an equivalent diameter of the interconnection parts between the second-level pore cavities is larger than 45% of an average value of a diameter of second-level pore cavities.