Nowadays,　photocatalysis　has　emerged　as　a　highly　promising　approach　for　the　selective　depolymerization　of　lignin　under　mild　conditions　due　to　its　ability　to　generate　reactive　species　with　high　redox　capabilities　in　a　single　step.　In　this　study,　a　ternary　nanocomposite　photocatalyst,　CdS-DETA/In(OH)3/Ag2S,　was　synthesized　using　in　situ　assembly　and　ion　exchange　methods.　This　approach　was　chosen　to　address　the　shortcomings　of　traditional　preparation　methods,　which　often　lead　to　the　mutual　coverage　or　occupation　of　different　materials,　making　it　difficult　to　achieve　synergistic　oxidation　and　reduction　of　lignin.　Compared　to　the　original　CdS-DETA,　In(OH)3,　and　CdS-DETA/In(OH)3,　the　constructed　ternary　nanocomposite　photocatalyst　was　found　to　form　a　unique　dual-S-scheme　heterojunction.　This　structure　not　only　effectively　enhances　light-harvesting　capabilities　but　also　enables　the　efficient　separation　and　transfer　of　photogenerated　charge　carriers.　Consequently,　the　photocatalyst　exhibits　good　photocatalytic　activity　in　the　depolymerization　of　the　lignin　model　compound　(2-phenoxy-1-phenylethanol).　The　mechanism　of　the　dual-S-scheme　heterojunction　in　the　photocatalyst　was　proposed,　and　its　effectiveness　in　improving　light　absorption　and　facilitating　the　separation　and　transfer　of　photogenerated　carriers　was　demonstrated.