The invention provides a transition metal nitride/nitrogen-doped graphene nanometer composite material and a preparation method and application thereof. In the composite material, transition metal nitride nanoparticles with sizes being 5-20 nanometers are embedded into a nitrogen-doped graphene framework, and the composite material is relatively large in specific area, contains mesopores uniformlydistributed and has favorable electrical conductivity. The preparation method of the composite material comprises the steps of (1) mixing a template precursor, a carbon source and a metal source to obtain a mixed material; and (2) placing the mixed material of the step (1) in an atmosphere furnace, and performing calcination in a non-oxidization atmosphere to obtain the transition metal nitride/nitrogen-doped graphene nanometer composite material. The composite material is used for the supercapacitor, a fuel cell or a lithium ion battery and has excellent application prospect. Compared with the prior art, the preparation method of the composite material is simple in process, low in equipment requirement and low in energy consumption, the raw material is low in cost, and mass production iseasy.