This　study　focuses　on　the　development　of　heterojunction　photocatalysts　for　the　efficient　utilization　of　solar　energy　to　address　the　energy　crisis　and　reduce　environmental　pollution.　Cadmium　sulfide　(CdS)/graphite-type　carbon　nitride　(g-C3N4)　nanocomposites　were　synthesized　using　a　hydrothermal　method,　and　their　photoelectrochemical　properties　and　photocatalytic　performance　for　hydrogen　evolution　reaction　(HER)　were　characterized.　Scanning　electron　microscope　images　showed　the　intimate　interface　and　caviar-like　nanoheterojunction　of　the　CdS　nanoparticles　on　g-C3N4　nanospheres,　suggesting　their　potential　involvement　in　the　photocatalytic　process.　Electrochemical　and　spectroscopic　analyses　were　conducted　to　confirm　the　roles　of　CdS　in　the　nanoheterojunction.　The　results　showed　that　10　wt%　CdS/g-C3N4　nanospheres　exhibited　higher　photocatalytic　activity　than　pure　g-C3N4　under　visible　light　irradiation.　A　HER　rate　of　655.5　mu　mol/g/h　was　achieved　after　three　photocatalytic　cycles,　signifying　good　photocatalytic　stability.　The　synergistic　effect　of　the　Z-scheme　heterojunction　formed　by　g-C3N4　and　CdS　was　identified　as　the　main　factor　responsible　for　the　enhanced　photocatalytic　performance　and　stability.　The　interface　engineering　effect　of　CdS/g-C3N4　facilitated　the　separation　of　photogenerated　electrons　and　holes.　This　study　provides　insights　into　the　design　and　fabrication　of　efficient　HER　photocatalysts.