Coordination　tunability　of　the　single-atom　catalysts　(SACs)　is　an　essential　but　challenging　issue　for　the　catalyst　sifting　and　structure-activity　relationship　analysis.　Herein,　Pt　single　atoms　with　tunable　coordination　are　readily　achieved　via　a　facile　cold-plasma　technique　by　changing　the　gas　type　(N-2,　Ar,　or　Air)　and　treatment　duration.　Combining　with　density　functional　theory　calculation,　the　Pt-N　coordination　concentration　is　predicted　to　be　highly　correlated　with　adsorption　free　energy　of　H*　atoms　(Delta　G(H*))　for　the　hydrogen　evolution　reaction　(HER),　which　is　further　validated　experimentally.　Remarkably,　the　sample　with　N,　O　co-dopant　introduced　by　air　plasma　exhibits　a　high　TOF　of　similar　to　13　H-2　s(-1)　at　40　mV,　and　outstanding　mass　activity　of　7.41　A　mg(Pt)(-1)　for　HER,　which　is　26.5　times　of　commercial　Pt/C　catalyst.　The　enhanced　performance　might　originate　from　the　optimized　electronic　structure　of　active　carbon　site　with　moderate　electron　transfer　and　p-band　center,　which　enables　a　suitable　binding　strength　with　H*　and　thus　a　near-zero　Delta　G(H*).