It　is　an　efficient　and　green　way　to　obtain　hydrogen　with　the　assistance　of　highly　active　and　low-cost　electrocatalysts　by　using　the　electrochemical　water　electrolysis　process　in　the　alkaline　electrolyte.　Herein,　MoO3　particles-decorated　Co(OH)(2)　nanosheet　array　with　a　hierarchical　nanostructure　wrapped　Ag　nanowires　(MoO3-Co(OH)(2)@Ag　NWs)　electrocatalysts　have　been　constructed　via　a　two-step　electrodeposition　method.　Ag　nano　wires　have　functioned　as　a　conductive　network　to　improve　electron　transportation　ability.　As-prepared　MoO3-Co　(OH)(2)@Ag　NWs　catalysts　show　good　HER　performance　compared　with　the　original　Co(OH)(2)　by　delivering　at　a　low　overpotential　of　220　mV　at　a　current　density　of　-100　mA　cm(-2),　while　those　for　pristine　Co(OH)(2)　and　MoO3　are　290　and　412　mV,　respectively.　The　good　durability　performance　of　the　MoO3-Co(OH)(2)@Ag　NWs　catalyst　can　last　for　29　h　at　a　high　current　density　of　100　mA　cm(-2)　with　negligible　loss,　demonstrating　the　possible　commercial　application　in　electrochemical　water　splitting.　A　theoretical　study　has　been　carried　out　to　understand　the　reaction　kinetics　in　the　generated　heterostructure　(MoO3-Co(OH)(2)),　which　can　significantly　promote　hydrogen　evolution　reaction　process　with　the　reduced　adsorption　energy　of　water　(Delta　G(H2O*))　and　decreased　Gibbs　free　energy　of　adsorbed　H*　(Delta　G(H*))　during　the　hydrogen　evolution　reaction　process.　This　work　can　help　us　to　design　high-active　catalysts　with　the　heterointerface-dependent　mechanism　for　electro-catalytic　water　splitting　processes.