Surface　plasmon　resonance　(SPR)　effect　of　metal　nanostructures　is　established　as　an　efficient　and　attractive　strategy　to　boost　visible-light　or　even　near-infrared-responsive　photo-electrochemical　(PEC)　water　splitting　devices　for　substantial　solar-to-chemical　energy　conversion.　Rational　integration　of　plasmonic　metal　nanostructures　with　semiconductors　in　an　appropriate　fashion　is　beneficial　for　creating　a　large　variety　of　plasmonic　metal/semiconductor　photoelectrodes.　However,　up　to　date,　construction　of　well-defined　and　highly　efficient　plasmonic　metal/semiconductor　heterostructures　is　still　in　its　infant　stage.　In　this　review,　basic　principles　of　PEC　water　splitting　over　semiconductors,　SPR-excited　plasmonic　effect　of　metal　nanostructures,　and　their　intrinsic　correlation　with　each　other　are　first　concisely　introduced.　Subsequently,　it　is　paid　great　attention　to　specifically　summarize　the　diverse　plasmonic　metal/semiconductor　photoelectrodes　currently　being　extensively　explored　for　indirect　plasmon-induced　PEC　water　splitting.　Particularly,　different　plasmonic　metal/semiconductor　nanoarchitectures　including　planar　thin　films,　1D　composited,　and　3D　spatially　hierarchical　heterostructures　are　systematically　classified　and　elucidated.　Finally,　future　perspectives　and　challenges　in　triggering　further　innovative　thinking　on　plasmon-enhanced　solar　water　splitting　are　envisaged.　It　is　anticipated　that　this　review　can　provide　enriched　information　on　rational　design　and　construction　of　various　plasmonic　metal/semiconductor　heterostructures　for　solar-powered　plasmon-based　PEC　devices.