Optimizing　structure　and　surface　morphologies　in　electrocatalyst　design　are　important　to　enhance　the　intrinsic　activity　of　the　hydrogen　evolution　reaction　(HER).　Mo-based　phosphides　and　carbides　have　been　confirmed　as　the　widely-reported　catalysts　for　HER.　However,　the　origin　of　their　enhanced　catalytic　activity　is　not　fully　clarified.　Herein,　the　np-FeMoC　and　np-FeMoP　with　a　self-supporting　nanoporous　structure　were　prepared　using　the　melt-spinning　and　dealloying　methods.　Benefiting　from　the　self-supporting　electrode,　nanoporous　structure,　abundant　active　species,　low　charge　-transfer　resistance　and　electron　synergy,　the　np-FeMoC　exhibits　good　catalytic　performance.　The　np-FeMoC　performs　a　low　overpotential　of　50.8　mV　at　10　mA　cm　-2　current　density　for　HER　in　1　M　KOH.　This　value　is　2.7　times　lower　than　that　of　the　np-FeMoP　sample,　indicating　a　synergistic　effect　between　Mo　2　C　and　Fe.　From　XPS　and　in-situ　Raman　results,　it　was　observed　that　the　dissolution　of　Mo　2　C　occurs　accompanied　by　dynamic　evolution　during　the　HER　process　on　the　np-FeMoC　surface.　This　work　unveils　the　intrinsic　activity　of　Mo-based　carbide　and　phosphide,　providing　valuable　guidance　for　reasonable　exploit　of　highperformance　HER　catalysts.