Developing　highly　efficient　catalysts　for　hydrogen　evolution　reaction　(HER)　play　a　significant　role　in　the　large-scale　application　of　electrochemical　water　splitting.　Here,　we　develop　an　ultrafine　ordered　Pt3Co　NPs　supported　on　N-doped　graphene　(NG),　which　achieves　high　HER　activity　with　a　small　overpotential　of　13　mV　at　10　mA　cm(-2).　More　importantly,　at　the　overpotential　of　20　mV,　the　ordered　Pt3Co　catalyst　(Pt3Co/NG-700)　indicates　19.0　and　51.8　times　mass　activity　than　that　of　the　disordered　Pt3Co　catalyst　(Pt3Co/NG)　and　commercialized　Pt/C　catalyst,　respectively.　Additionally,　the　Pt3Co/NG-700　electrocatalyst　displays　outstanding　long-term　stability　under　harsh　chronopotentiometry　and　cycling　tests　in　the　acidic　media.　The　theory　calculations　reveal　that　the　extraordinary　HER　performance　on　Pt3Co/NG-700　electrocatalyst　originates　from　the　charge　redistribution　of　Pt　induced　by　Co　in　the　structurally　ordered　Pt3Co　intermetallic.　The　charge　redistribution　of　Pt　facilitates　the　adsorption　and　dissociation　of　H*　and　provides　a　higher　electron　transfer　and　better　conductivity,　resulting　in　high　HER.　Our　work　opens　new　opportunities　to　design　noble　based　alloy　catalysts　for　highly　efficient　HER.