The invention relates to a preparation method of a medical porous metal material substituting for a dental bone. The preparation method comprises the steps of mixing tantalum powder, a pore-forming agent and a forming agent to form mixed powder, and further pressing the powder into an organic foam body for forming, degreasing, sintering, cooling and performing heat treatment to prepare a porous tantalum material, wherein the press-forming pressure is 50-100Mpa, the pore-forming agent is one or more of urea, sodium chloride, ethyl cellulose and methyl cellulose, and the forming agent is one or more of stearic acid, zinc stearate, paraffin wax and synthetic rubber. According to the preparation method provided by the invention, tests prove that in the final porous tantalum material, the impurity content can be lower than 0.2%, the density can achieve 11.67-13.34g / cm<3>, the porosity can achieve 20-30%, and the pore diameter can achieve 5-30mu m; the elastic modulus can achieve 4.5-6.0Gpa, the bending strength can achieve 110-130Mpa, and the compressive strength can achieve 100-130Mpa. The porous tantalum material provided by the invention is very suitable for the medical implant material substituting for the dental bone.