A　new　proposal　for　designing　sensitive　photoeletrochemical　sensor　with　a　ternary　hybrid　film　developed　by　absorbing　hematin　on　carbon　nanohorns　superstructures　and　poly-L-lysine　complex　support　to　achieve　quantificational　detection　of　4-hydrox-3-nitrobenzenenearsonic　acid　(HNBAA)　was　offered.　Here,　hematin　with　easy　acquirement,　good　biocompatibility　and　strong　visible　light　harvesting　capability,　was　introduced　as　photosensitizer　for　photoelectrochemical　determination.　Additionally,　the　complex　support　composed　by　fascicled　superstructures　of　carbon　nanohorns　which　possessed　many　superiors,　such　as　excellent　electronic　conductivity,　large　specific　area　and　adsorption　etc.,　and　poly-L-lysine　which　could　form　hydrogen　bond　with　hematin　performed　excellent　immobilization　action　of　hematin.　Due　to　the　synergistic　effect　and　surface　enhancement　effect,　complex　support　provided　a　charge-transfer　matrix　to　catch　and　transport　excited　electron　from　hematin　rapidly,　which　was　benefit　to　baffle　photo-generated　electron-hole　recombination　and　improve　photoelectrochemical　signal　in　visible　light　region　effectively.　HNBAA,　as　a　photogenerated　hole　scavenger,　enhanced　the　photoelectrochemical　response　again.　Furthermore,　the　excellent　sensitivity　and　broad　linear　detection　range　to　HNBAA　of　this　sensor　with　good　stability　and　high　selectivity,　satisfied　reproducibility　and　acceptable　accuracy　was　propitious　to　practical　application　of　sample　analysis,　and　the　good　biocompatibility　of　modified　materials　and　low　applied　potential　on　this　sensor　laid　a　foundation　for　its　promising　application.　(C)　2015　Elsevier　B.V.　All　rights　reserved.