Abstract: The invention belongs to the technical field of advanced material preparation, provides a method for preparing nano-diamond by high-current pulsed electron beam. Nano-carbon is selected as raw material, and metal catalyst is added by two processes: (1) metal catalyst is deposited on nano-carbon by electroless plating, and nano-carbon plated with metal catalyst is mixed with nano-carbon; (2) Catalyst metal is evaporated by arc discharge in carbon-containing atmosphere to obtain carbon-coated metal nanoparticles. The mixed powders were pressed into flakes at a pressure of 20-50 MPa and kept for 1-10 min, then bombarded with an electron gun for 5-15 times under the conditions of electron beam intensity of 10 kA, energy of 27 keV and pulse width of 3.6 μs, and finally collected and purified. In the method of the invention, the adding mode of the metal catalyst can maximize the catalytic effect of the catalyst; The high energy density of electron beam and the change of micro-phase are beneficial to the transformation of diamond and improve the conversion rate.