Abstract: The present invention belongs to the field of superhard material preparation technology, and discloses a method of preparing a self-supported boron-doped diamond catalytic material. The method utilizes the conventional chemical vapor deposition deposition method to prepare a block material by improving the state of the substrate material, mechanical mixing of activated treated silicon nanoparticles, boron nanoparticles or boron-containing compounds, and diamond nanoparticles, and cold isostatic pressing, while achieving self-supporting and boron-doping of diamond materials. The invention can directly obtain self-supporting diamond material without subsequent treatment; boron is doped by using the principle of high temperature diffusion to achieve doping, with simple process, low cost, high efficiency, safety and environmental protection, and the removed substrate material can also be reused.