The　graphitic　carbon　nitride　(g-C3N4)　is　regarded　as　a　powerful　support　for　constructing　heterojunction.　How　to　rationally　design　high-performance　g-C3N4-based　heterojunction　remains　a　great　challenge.　In　this　work,　a　kind　of　spatial　distribution　heterojunction　is　prepared　by　in　situ　growing　ZnIn2S4　(ZIS)　nanosheets　on　g-C3N4　microtubes　(T-CN).　To　highlight　the　advantage　of　such　a　structure　design,　g-C3N4　bulk　(B-CN)　and　g-C3N4　nanosheets　(S-CN)　are　also　used　as　the　supports　to　obtain　B-CN/ZIS　bulk　heterojunction　and　S-CN/ZIS　2D/2D　heterojunction,　respectively.　T-CN/ZIS　spatial　distribution　heterojunction　combines　the　hierarchical　core/shell　structure　of　BCN/ZIS　and　ultrathin　structure　of　S-CN/ZIS,　which　is　much　favorable　for　photocatalytic　CO2　reduction.　It　is　found　that　the　gas　yield　from　CO2　reduction　is　highest　over　T-CN/ZIS,　which　is　3.5　and　1.5　times　higher　than　B-CN/ZIS　and　S-CN/ZIS.　The　experimental　results　manifest　that　the　spatial　distribution　of　ZIS　nanosheets　on　T-CN　induces　stronger　photoabsorption,　faster　interfacial　charge　transfer,　and　larger　CO2　adsorption,　all　of　which　are　responsible　for　the　best　catalytic　activity.　It　is　expected　that　this　work　will　provide　an　instructive　guideline　for　designing　g-C3N4-based　heterojunction.