Photocatalysis　is　a　promising　strategy　for　the　treatment　of　dangerous　chemical　pollutants　in　the　ocean.　In　this　work,　a　stable　copper-based　photocatalyst,　i.e.,　{[Cu(BPA)2]2I3}n　(1,　BPA　=　4,4　＇-bipyridinium-N-pentanoic　acid),　exhibited　excellent　degradation　performance　in　dye　pollutant　in　seawater.　According　to　the　structural　analysis,　this　photocatalyst　consists　of　1-D　cationic　[Cu(BPA)2]n2n+　infinite　chain　and　two　I3-　polyiodide　anions.　In　the　[Cu(BPA)2]n2n+　chain,　the　distorted　CuO4N2　octahedra　are　bridged　by　asymmetric　viologen　ligand　(BPA),　which　result　in　a　1-D　ladder-shaped　chain.　Strong　C-HO/I　hydrogen　bonds　contribute　to　the　formation　of　a　2-D　layer　along　bc-plane,　in　which　I3-　anions　are　stacked　among　the　cationic　chains.　The　strong　adsorption　from　ultraviolet　to　visible　regions　together　with　its　high　charge　separation　efficiency　implies　its　usage　as　excellent　visible-light-driven　catalysis.　Interestingly,　good　photocatalytic　performance　for　the　degradation　of　Rhodamine　B　(RhB)　in　seawater　can　be　observed　by　using　this　hybrid　as　photocatalyst.　In　detail,　90.6%　degradation　ratio　of　RhB　can　be　achieved　in　150　min　under　visible　light,　which　was　monitored　on　a　UV-Vis　spectrum.　This　work　could　pave　the　way　for　new　ocean　pollutant　treatments　for　shipping　accidents.