A low-platinum catalyst based on nitride nanoparticles and a preparation method thereof. A component of an active metal of the catalyst directly clades on a surface of nitride particles or a surface of nitride particles loaded on a carbon support in an ultrathin atomic layer form. Preparation steps including: preparing a transition-metal ammonia complex first, nitriding the obtained ammonia complex solid under an atmosphere of ammonia gas to obtain nitride nanoparticles; loading the nitride nanoparticles on a surface of a working electrode, depositing an active component on a surface of the nitride nanoparticles by pulsed deposition, to obtain the low platinum loading catalyst using a nitride as a substrate. The catalyst may be used as an anode or a cathode catalyst of a low temperature fuel cell.