The invention discloses transition metal ammonia complex functionalized polydopamine, and a preparation method and application thereof. The transition metal ammonia complex functionalized polydopamineis prepared by reacting transition metal ammonia complex ions with dopamine. A transition metal-inlaid nitrogen-doped graphite carbon composite is prepared by heat treatment of the transition metal ammonia complex functionalized polydopamine. The transition metal ammonia complex functionalized polydopamine provided by the invention has strong uniform coating ability and has good application prospects in the field of nanocoatings. The transition metal-inlaid nitrogen-doped graphite carbon composite provided by the invention has the advantages of uniformly inlaying of active metal, abundant nanoporous structures, a large specific surface area, rich active sites and good conductivity, and has good application prospects in the fields of conductive materials, lithium battery negative electrodematerials, metal-air battery positive electrode materials, oxygen reduction catalysts, hydrogen evolution catalysts oxygen, evolution catalysts and the like.