Photocatalytic　reduction　of　carbon　dioxide　has　attracted　remarkable　attention.　However,　the　photocatalytic　efficiency　is　restricted　to　the　poor　capacity　of　adsorption　and　activation　for　CO2　molecules　on　the　surface　of　catalyst.　Herein,　La　isomorphous　substituted　BiOBr　is　prepared　by　a　convenient　chemical　method　with　La3+　replacing　Bi3+.　For　CO2　photoreduction,　the　La-substituted　BiOBr　shows　CO　yield　of　154.4　mu　mol　center　dot　g-　1　center　dot　h-1,　being　7.1-fold　as　higher　as　original　BiOBr.　Experimental　and　calculation　results　manifest　that　surface　frustrated　Lewis　acid　and　base　sites　of　La3+-O2-pairs　are　formed　on　the　surface　of　BiOBr　with　adulteration　of　La　and　increased　oxygen　vacancies,　which　could　be　conductive　to　the　adsorption　and　activation　for　CO2　molecules.　This　work　not　only　suggests　a　possible　mechanism　for　photocatalytic　reduction　of　CO2,　but　also　opens　up　a　new　opportunity　for　the　preparation　of　efficient　catalysts　for　CO2　reduction.