Herein,　a　series　of　three-dimensionally　ordered　macroporous　(3DOM)　Bi4O5Br2　photocatalysts　with　different　macropore　sizes　were　successfully　fabricated　via　a　polymethyl　methacrylate　(PMMA)　template　method.　The　photocatalytic　activity　for　phenol　degradation　over　3DOM　Bi4O5Br2　first　increased　and　then　decreased　with　the　rise　in　macropore　size.　Specifically,　3DOM　Bi4O5Br2-255　(macropore　diameter　ca.　170　nm)　exhibits　the　best　photocatalytic　activity　in　the　static　system,　which　is　about　4.5,　7.3,　and　11.9　times　higher　than　those　of　bulk　Bi4O5Br2,　Bi2WO6,　and　g-C3N4,　respectively.　Meanwhile,　high　phenol　conversion　(75%)　is　also　obtained　over　3DOM　Bi4O5Br2-255　in　the　flow　system　under　full　spectrum　irradiation.　Furthermore,　3DOM　Bi4O5Br2-255　also　shows　strong　mineralization　capacity　owing　to　the　downward　shift　of　valance　band　position　(0.15　V)　as　compared　with　Bi4O5Br2.　Total　organic　carbon　(TOC)　removal　rate　over　3DOM　Bi4O5Br2-255　(62%)　is　much　higher　than　that　of　Bi4O5Br2　(17%).　The　enhancement　in　photocatalytic　performance　of　3DOM　Bi4O5Br2-255　is　attributable　to　its　better　phenol　adsorption,　O2　activation,　and　charge　separation　and　transfer　abilities.　This　work　combines　the　advantages　of　3D　structure　and　surface　dangling　bonds,　providing　new　possibilities　for　designing　highly　efficient　photocatalysts　for　pollutants　removal.[Figure　not　available:　see　fulltext.].　©　2023,　Tsinghua　University　Press.