Abstract: The present invention belongs to the field of new material synthesis and provides a method for the preparation of boron-doped diamond powder. The ethanol solution of boron source is ultrasonically shaken to form a dispersion, dropped onto the carrier and dried to obtain the substrate; the diamond film is prepared by HFCVD method, and the substrate is finely purified and activated under 100% hydrogen environment, and the activation treatment time is 20-40 min; during the activation treatment and diamond film deposition, the temperature is maintained at 2000 -2200℃, the substrate temperature is 650-950℃, the total pressure in the reaction chamber is 20-70Torr, the methane concentration is 0.5%-2%, the deposition time is 1-6h. The diamond film is placed in a tube furnace, vacuumed and then fed with protective gas and diffusion annealed. This method has the advantages of simplicity, convenience, safety and controlled amount of boron doping. It is especially suitable for the preparation of BDD electrodes as fuel cell cathode catalysts.