Methods　based　on　photoelectrochemistry　have　been　developed　for　immunoassay,　but　most　involve　in　a　low　sensitivity　and　a　relatively　narrow　detectable　range.　Herein　a　new　bio-bar-code-based　split-type　photoelectrochemical　(PEC)　immunoassay　was　designed　for　sensitive　detection　of　prostate-specific　antigen　(PSA),　coupling　rolling　circle　amplification　(RCA)　with　enzymatic　biocatalytic　precipitation.　The　bio-bar-code-based　immunoreaction　was　carried　out　on　monoclonal　anti-PSA　antibody　(mAb(1))-coated　microplate　using　primer　DNA　and　polyclonal　anti-PSA　antibody-conjugated　gold　nanoparticle　(pDNA-AuNP-pAb(2))　with　a　sandwich-type　assay　format.　Accompanying　the　immunocomplex,　the　labeled　primer　DNA　on　gold　nanoparticle　readily　triggered　RCA　reaction　in　the　presence　of　padlock　probe/dNTPs/ligase/polymerase.　The　RCA　product　with　a　long　single　stranded　DNA　could　cause　the　formation　of　numerous　hemin/G-quadruplex-based　DNAzyme　concatamers.　With　the　assistance　of　nicking　endonuclease,　DNAzyme　concatamers　were　dissociated　from　gold　nanoparticle,　which　catalyzed　the　precipitation　of　4-chloro-l-naphthol　in　the　presence　of　H2O2　onto　CdS　nanorods-coated　electrode　(as　the　photoanode　for　the　generated　holes).　The　formed　insoluble　precipitate　inhibited　the　electron　transfer　from　the　solution　to　CdS　nanorods-modified　electrode　by　using　ascorbic　acid　as　the　electron　donor.　Under　the　optimum　conditions,　the　photocurrent　of　the　modified　electrode　decreased　with　the　increasing　of　PSA　concentration.　A　detectable　concentration　for　target　PSA　with　this　system　could　be　achieved　as　low　as　1.8　pg　mL(-1)　In　addition,　our　strategy　also　showed　good　reproducibility,　high　specificity　and　accuracy　matched　well　with　commercial　PSA　ELISA　kits　for　real　sample　analysis.　These　remarkable　properties　revealed　that　the　developed　PEC　immunoassay　has　great　potential　as　a　useful　tool　for　the　detection　of　PSA　in　practical　application.