Photosynthesis　of　hydrogen　peroxide　(H2O2)　represents　a　green　and　cost-effective　approach.　However,　achieving　dual-channel　photocatalytic　oxygen　reduction　reaction　(ORR)　and　water　oxidation　reaction　(WOR)　faces　huge　challenges　due　to　sluggish　carrier　transfer　and　unfavourable　WOR　thermodynamics　for　most　photocatalysts.　Herein,　a　piezoelectric　Step-scheme　heterojunction　comprising　BaTiO3　nanowires　and　CdS　nanoclusters　(BTNWCdS　heterostructures)　is　designed　for　efficient　dual-channel　H2O2　production.　By　harnessing　the　polarization　electric　field　of　BTNW,　an　enhanced　H2O2　production　rate　of　6454.4　mu　mol　g-1h-1　is　achieved　in　the　piezophotocatalytic　process　by　applying　the　visible　light　and　ultrasound,　which　is　15.28　times　and　1.68　times　higher　than　that　of　piezocatalysis　and　photocatalysis　alone,　respectively.　Mechanism　analysis　confirms　that　the　internal　electric　field　of　BTNW-CdS　heterostructures　not　only　facilitates　two-electron　ORR　by　improving　charge　separation　efficiency,　but　also　overcomes　the　high　uphill　thermodynamics　of　direct　two-electron　WOR.　Notably,　the　incorporation　of　lactic　acid　reacts　with　photogenerated　holes　to　produce　protons,　which　further　facilitates　ORR.　Our　findings　demonstrate　the　potential　of　utilizing　the　built-in　electric　field　of　piezoelectrics　to　promote　charge-carrier　separation　and　enhance　photocatalytic　efficiency.