The　rational　construction　of　heterostructures　by　using　layered　semiconductors　with　two-dimensional　(2D)　nanosheet　configurations　is　promising　to　improve　the　efficiency　of　CO2　photoreduction.　Herein,　the　fabrication　of　layered　heterojunction　photocatalysts　(PCN/ZnIn2S4)　by　in　situ　growth　of　2D　ZnIn2S4　nanosheets　on　the　surfaces　of　ultrathin　polymeric　carbon　nitride　(PCN)　layers　is　presented　for　greatly　enhanced　CO2　conversion　with　visible　light.　The　solution-processed　self-assembly　strategy　renders　the　building　of　uniform　and　intimate　junctions　between　PCN　layers　and　ZnIn2S4　subunits,　which　remarkably　accelerates　the　separation　and　transfer　of　photogenerated　charge　carriers.　In　addition,　the　layered　composites　can　also　promote　CO2　adsorption　and　strengthen　the　visible-light　absorption.　Consequently,　the　optimized　PCN/ZnIn2S4　sheet-shaped　composite　shows　reinforced　photoactivity　for　deoxygenative　CO2　conversion,　affording　a　high　CO-production　rate　of　44.6　mu　mol　h(-1),　which　is　223　times　higher　than　that　of　the　pristine　PCN　nanosheets.　Moreover,　the　heterojunction　photocatalyst　also　exhibits　high　stability　during　repeated　runs　for　five　cycles.