Two-dimension　nanosheets　are　ideal　photocatalysts　for　CO2　reduction　due　to　their　high　exposure　of　active　sites　and　short　charge　transfer　pathway.　However,　2D　photocatalysts　have　a　tendency　to　agglomeration,　thus　compromising　the　performance　of　photocatalytic　CO2　reduction.　Trees,　one　of　the　most　important　plants　for　photosynthesis,　have　a　unique　＂leaf-on-branch＂　structure.　This　unique　two-dimension/one-dimension　(2D/1D)　configuration　maximizes　the　adsorption　of　CO2　molecules　and　light　harvesting.　Herein,　a　tree-inspired　semiconductor-on-ceramic　2D/1D　heterostructure　for　efficient　photocatalytic　CO2　reduction　is　reported.　The　cobalt　silicate　(CoSi)　nanosheets　(similar　to　0.68　nm)　are　in　situ　grown　on　the　surfaces　of　hydroxyapatite　(HAP)　nanowires,　creating　a　well-defined　2D/1D　hierarchical　structure.　The　vertical　alignment　of　ultrathin　CoSi　nanosheets　on　the　HAP　nanowires　effectively　suppresses　their　agglomeration,　leading　to　a　large　BET　surface　area　(106.45　m(2)/g)　and　excellent　CO2　adsorption　(8.00　cm(3)　g(-1)).　The　results　of　photoelectrochemical　characterization　demonstrate　that　the　2D/1D　hierarchical　structure　is　powerful　to　expedite　charge　transfer.　As　a　result,　the　gas　generation　rate　of　CO　is　as　high　as　28780　mu　mol　g(-1)　h(-1)　over　the　CoSi-on-HAP　2D/1D　heterostructure.　In　addition,　the　electron　transfer　mechanism　and　reaction　pathways　of　CO2　reduction　are　revealed　by　in　situ　irradiated　XPS　and　in　situ　DRIFT　spectra.