This　work　designed　a　liposome-mediated　photocurrent　polarity　switching　immunosensor　depending　on　the　reversed　photocurrent　of　iodine-doped　BiOCl　(I-BOC)　nanoflowers　induced　by　the　released　methylene　blue　(MB)　for　the　detection　of　prostate-specific　antigen　(PSA).　Initially,　MB-loaded　liposomes　as　indicators　were　confined　within　the　microplates　to　participate　in　the　sandwiched　immunoreaction　and　lysed　under　the　treatment　of　Triton　X-100　to　release　numerous　MB.　Owing　to　the　host-guest　recognition　between　beta-cyclodextrin　(beta-CD)　and　MB,　the　released　MB　was　immobilized　on　the　beta-CD-modified　I-BOC/FTO　electrode　and　triggered　the　photocurrent　polarity　reversal　from　cathodic　photocurrent　to　anodic　photocurrent.　The　sensing　platform　realized　an　accurate　and　sensitive　assay　of　PSA　due　to　the　effective　elimination　of　false-positive/negative　signals　in　a　linear　range　of　0.02-50　ng　mL-1　with　a　limit　of　detection　of　12　pg　mL-1.　Furthermore,　this　work　not　only　conjugated　liposomeassisted　signal　amplification　strategy　with　the　photocurrent　polarity　switching　system　but　also　provided　a　novel　pathway　for　various　protein　determinations.