The　construction　of　high-performance　and　stable　nanocomposite　photocatalyst　remains　a　great　challenge　toward　photocatalytic　hydrogen　evolution　reaction,　which　is　mainly　due　to　the　mediocre　interfacial　contact　between　the　cocatalyst　and　the　host.　In　this　work,　ultrasmall　NiS　is　highly　dispersed　on　HNb3O8　2D　nanosheet　via　a　facile　electrostatic　adsorption/self-assembly　process.　Interestingly,　the　growth　of　NiS　is　greatly　suppressed　by　the　interlayered　spatial　steric　inhibition　effect　and　a　strong　interaction　between　NiS　and　HNb3O8　nanosheet　is　formed.　While　the　modification　of　NiS　by　the　traditional　methods,　such　as　the　coprecipitation　and　mechanical　mixing　methods,　could　not　generate　the　sub-nanometer　size　of　NiS　with　the　tight　contract　between　NiS　and　HNb3O8　nanosheet.　As　a　result,　the　recombination　of　the　photogenerated　carriers　is　greatly　suppressed　on　the　sample　prepared　by　our　method.　Furthermore,　the　overpotential　of　hydrogen　evolution　reaction　could　also　be　reduced　significantly.　Thus,　the　as-prepared　composite　exhibits　a　markedly　improved　photocatalytic　H2　evolution　activity　as　well　as　considerable　stability.　The　optimal　sample　shows　the　H2　evolution　rate　of　1519.4　μmol　g−1　h−1,　which　is　about　17.4　times　higher　than　that　of　the　bare　HNb3O8　nanosheets.　The　activity　is　also　a　magnitude　higher　than　that　of　the　sample　prepared　by　a　mechanical　mixing　method.　Additionally,　NiS/HNb3O8　prepared　by　the　developed　method　shows　a　comparable　activity　as　well　as　overpotential　with　Pt/HNb3O8,　indicating　an　alternative　to　platinum.　©　2018　Elsevier　B.V.