Rational　heterostructure-design　in　electrocatalysts　represents　a　promising　approach　toward　high　performance　in　the　electrocatalytic　hydrogen　evolution　reaction　(HER).　In　specific,　optimizing　the　H　adsorption　behavior　at　the　surface/interface　of　heterostructure　is　of　key　importance　to　improve　the　catalytic　performance.　Herein,　we　demonstrate　the　construction　of　a　heterostructure　from　a　well-defined　oxygenbridged　Co/Mo　heterometallic　zeolitic　imidazolate　framework　(MOZ)　as　an　efficient　electrocatalyst　for　HER.　The　optimized　hybrid　exhibits　high　catalytic　activity　and　stability　in　electrolytes　with　a　wide　pH　range.　Detailed　XPS,　XAS　and　theoretical　studies　reveal　that　the　regulation　of　metal　species　can　tailor　the　lattice　of　Mo2C　within　the　hybrid　and　induce　the　formation　of　defect　sites,　which　could　not　only　induce　surface　charge　transfer　between　the　atoms　and　provide　an　additional　active　site,　but　also　affect　the　H　adsorption　behavior　at　the　interface　of　a　heterostructure.　This　work　provides　an　effective　strategy　to　design　a　heterostructure　with　tailored　active　sites　for　energy　conversion.　(C)　2020　Science　Press　and　Dalian　Institute　of　Chemical　Physics,　Chinese　Academy　of　Sciences.　Published　by　ELSEVIER　B.V.　and　Science　Press.　All　rights　reserved.