Developing　efficient　photocatalysts　is　one　of　green　and　low　cost　tactic　for　addressing　the　environmental　deterioration　and　energy　crisis.　Therefore,　it　remains　a　fantastic　and　important　strategy　to　design　an　efficient　junction　between　different　semiconductors　for　harvesting　solar　light,　boosting　the　redox　capability.　Herein,　the　fabrication　of　ZnS　in　situ　decorated　CdIn2S4　(referred　to　as　CIS-Zx)　were　prepared　by　converting　ZnS　particles　on　Cd2In4S　surface　by　a　facile　cation　exchange　method　during　solvothermal　synthesis.　According　to　a　series　of　PEC　measurements　and　DFT　calculations,　the　bending　of　band　edge　as　well　as　the　establishing　of　built-in　electric　field　in　the　interface　of　CIS/ZnS　heterojunction　were　concluded,　causing　the　formation　of　in-situ　S-scheme　heterojunctions　in　CdIn2S4/ZnS.　The　in-situ　S-scheme　heterojunctions　can　effectively　ameliorate　the　migration　behaviors　of　photo-generated　charges.　Compared　with　pure　CdInS4,　ZnS　and　physically　mixed　CdIn2S4/ZnS,　the　CIS-Zx　in-situ　S-scheme　heterojunction　exhibits　efficient　photocatalytic　activity　and　stability　in　the　selective　reduction　of　aromatic　nitro　compounds　and　oxidation　of　aromatic　alcohols,　it　is　hoped　that　this　work　will　open　up　a　new　avenue　for　innovative　applications　of　in-situ　S-scheme　heterojunctions.