The invention discloses a nitrogen-doped carbon sphere/graphene/platinum nanoparticle ternary composite material and a preparation method and an application thereof. The preparation method comprises the following steps of 1) performing heat treatment on a carbon-containing nitrogen source to obtain nitrogen-doped carbon spheres; 2) coating the surface of glassy carbon with a nitrogen-doped carbon sphere solution to form a nitrogen-doped carbon sphere-modified glassy carbon electrode; 3) dispersing graphene oxide into a buffer solution to form a graphene oxide solution, in the graphene oxide solution, performing electrodeposition through cyclic voltammetry (CV) by taking the nitrogen-doped carbon sphere-modified glassy carbon electrode as a working electrode, taking a platinum electrode as a counter electrode and taking a calomel electrode as a reference electrode to obtain a graphene/nitrogen-doped carbon sphere-modified glassy carbon electrode; and 4) immersing the graphene/nitrogen-doped carbon sphere-modified glassy carbon electrode into a platinum-containing electrolyte and performing constant-potential electrodeposition treatment to obtain the nitrogen-doped carbon sphere/graphene/platinum nanoparticle ternary composite material. The method is clean and effective without damaging the big laminated structure of graphene.