Photocatalytic　hydrogen　production　is　considered　as　an　ideal　approach　to　solve　global　energy　crisis　and　environmental　pollution.　Graphitic　carbon　nitride　(g-C3N4)　has　received　extensive　consideration　due　to　its　facile　synthesis,　stable　physicochemical　properties,　and　easy　functionalization.　However,　the　pristine　g-C3N4　usually　shows　unsatisfactory　photocatalytic　activity　due　to　the　limited　separation　efficiency　of　photogenerated　charge　carriers.　Generally,　introducing　semiconductors　or　co-catalysts　to　construct　g–C3N4–based　heterojunction　photocatalysts　is　recognized　as　an　effective　method　to　solve　this　bottleneck.　In　this　review,　the　advantages　and　characteristics　of　various　types　of　g–C3N4–based　heterojunction　are　analyzed.　Subsequently,　the　recent　progress　of　highly　efficient　g–C3N4–based　heterojunction　photocatalysts　in　the　field　of　photocatalytic　water　splitting　is　emphatically　introduced.　Finally,　a　vision　of　future　perspectives　and　challenges　of　g–C3N4–based　heterojunction　photocatalysts　in　hydrogen　production　are　presented.　Predictably,　this　timely　review　will　provide　valuable　reference　for　the　design　of　efficient　heterojunctions　towards　photocatalytic　water　splitting　and　other　photoredox　reactions.　©　2021　The　Author(s)