Cocatalysts　in　photocatalytic　systems　play　an　important　role　in　achieving　efficient　charge　separation.　These　cocatalysts　usually　have　a　small　size　and　are　generally　anchored　onto　main　catalysts.　They　are　taken　as　active　centers　to　receive　photogenerated　electrons　for　water　splitting.　However,　their　high　loading　concentration　usually　leads　to　the　degradation　of　water　splitting.　Here,　we　present　a　different　strategy　for　the　design　of　the　main　catalyst　and　cocatalyst.　We　used　small-sized　ultrathin　cadmium　sulfide　(CdS)　nanosheets　as　the　main　catalysts　and　anchored　them　onto　large-sized　N　-doped　carbon　nanotubes　with　encapsulated　cobalts.　The　photocatalytic　hydrogen　production　of　our　optimized　composite　is　similar　to　21.8　mmol/g,　similar　to　3　times　higher　than　that　of　pure　CdS.　Mechanism　study　shows　that　photoelectrons　can　be　transferred　from　CdS　to　N-doped　carbon　nanotubes,　thus　achieving　fast　charge　separation　and　efficient　hydrogen　production.