Solid　non-conjugated　polymers　have　long　been　regarded　as　insulators　due　to　deficiency　of　delocalized　π　electrons　along　the　molecular　chain　framework.　Up　to　date,　origin　of　insulating　polymer　regulated　charge　transfer　has　not　yet　been　uncovered.　In　this　work,　we　unleash　the　root　origin　of　charge　transport　capability　of　insulating　polymer　in　photocatalysis.　We　ascertain　that　insulating　polymer　plays　crucial　roles　in　fine　tuning　of　electronic　structure　of　transition　metal　chalcogenides　(TMCs),　which　mainly　include　altering　surface　electron　density　of　TMCs　for　accelerating　charge　transport　kinetics,　triggering　the　generation　of　defect　over　TMCs　for　prolonging　carrier　lifetime,　and　acting　as　hole-trapping　mediator　for　retarding　charge　recombination.　These　synergistic　roles　contribute　to　the　charge　transfer　of　insulating　polymer.　Our　work　opens　a　new　vista　of　utilizing　solid　insulating　polymers　for　maneuvering　charge　transfer　toward　solar　energy　conversion.　©　2024　Dalian　Institute　of　Chemical　Physics,　the　Chinese　Academy　of　Sciences