The　strong　interaction　between　hetero　materials　interface　is　crucial　to　boost　the　transfer　efficiency　of　photo　-generated　electrons.　Herein,　the　dual-core@shell　structured　Bi2O3/Bi2WO6@g-C3N4　(BB@CN)　photocatalysts　were　fabricated　by　the　co-grind　and　calcination　method.　The　separation/transfer　efficiencies　of　photogenerated　electron-hole　pairs　could　be　improved　via　the　EXAFS　(Extended　X-ray　Absorption　Fine　Structure)　proved　strong　interaction　of　core/shell　interface.　The　BB@CN　catalysts　with　a　strong　interaction　interface　exhibit　high　activity　for　CO2-to-CO,　and　the　BB@10CN　(10　g　melamine　is　used)　catalyst　has　the　largest　formation　rate　(263.7　mu　mol　g-1)　and　selectivity　(97.0%)　of　CO　product.　Based　on　the　results　of　in-situ　DRIFTS　(Diffuse　Reflectance　Infrared　Fourier　Transform　Spectroscopy)　and　Density　Functional　Theory　calculation,　the　photoconversion　mechanism　of　CO2-to-CO　has　been　proposed:　the　COOH*　formation　is　the　rate-determined　step　of　CO2　conversion,　and　the　selectivity　of　CO　product　is　dependent　on　its　suitable　desorption　energy.　It　inspires　the　fabrication　strategy　of　efficient　hetero　photocatalysts　with　a　strong　interaction　interface　for　selective　photocatalytic　CO2　conversion.