The invention relates to a porous material and a preparation method thereof, and discloses a preparation method of a silk fibroin porous three-dimensional material. The preparation method comprises the following steps: sealing a silk fibroin aqueous solution for cultivation, then uniformly mixing with alcohol, freezing to directly obtain a water-insoluble silk fibroin porous bracket material, then regulating the secondary structure and the mechanical properties of the porous bracket by selectively using a post-treatment means, controlling the porosity, the aperture size and the like of the porous material by changing the concentration, the freezing temperature and other parameters of the silk fibroin, and finally removing the alcohol to obtain a pure silk fibroin porous bracket. The preparation process of the invention has the advantages of moderate conditions, no need of adding any crosslinking agent, hole-making agent and other toxic organic solvents, convenient control and easy industrialization, can effectively keep the biocompatibility of the silk fibroin, and can be used for repairing tissues such as bones, cartilages, ligaments, nerves, skins and the like and drug slow-releasing carriers and the like.