The　design　and　synthesis　of　a　Z-schematic　photocatalytic　heterostructure　with　an　intimate　interface　is　of　great　significance　for　the　migration　and　separation　of　photogenerated　charge　carriers,　but　still　remains　a　challenge.　Here,　we　developed　an　efficient　Z-scheme　organic/inorganic　g-C3N4/LDH　heterojunction　by　in　situ　growing　of　inorganic　CoAl-LDH　firmly　on　organic　g-C3N4　nanosheet　(NS).　Benefiting　from　the　two-dimensional　(2D)　morphology　and　the　surface　exposed　pyridine-like　nitrogen　atoms,　the　g-C3N4　NS　offers　efficient　trap　sits　to　capture　transition　metal　ions.　As　such,　CoAl-LDH　NS　can　be　tightly　attached　onto　the　g-C3N4　NS,　forming　a　strong　interaction　between　CoAl-LDH　and　g-C3N4　via　nitrogen-metal　bonds.　Moreover,　the　2D/2D　interface　provides　a　high-speed　channel　for　the　interfacial　charge　transfer.　As　a　result,　the　prepared　heterojunction　composite　exhibits　a　greatly　improved　photocatalytic　H-2　evolution　activity,　as　well　as　considerable　stability.　Under　visible　light　irradiation　of　4　h,　the　optimal　H-2　evolution　rate　reaches　1952.9　mu　mol　g(-1),　which　is　8.4　times　of　the　bare　g-C3N4　NS.　The　in　situ　construction　of　organic/inorganic　heterojunction　with　a　chemical-bonded　interface　may　provide　guidance　for　the　designing　of　high-performance　heterostructure　photocatalysts.