The　development　of　rapid　screening　sensing　platforms　to　improve　pre-screening　mechanisms　in　community　healthcare　is　necessary　to　meet　the　significant　need　for　portable　testing　in　biomarker　diagnostics.　Here,　we　designed　a　portable　smartphone-based　photoelectrochemical　(PEC)　immunoassay　for　carcinoembryonic　antigen　(CEA)　detection　using　Cu　-doped　ultrathin　porous　Bi　2　WO　6　(CuBWO)　nanosheets　as　the　photoactive　material.　The　CuBWO　nanosheets　exhibit　a　fast　photocurrent　response　and　excellent　electrical　transmission　rate　under　UV　light　due　to　their　surface　plasmon　resonance　effect　(SPR).　The　method　uses　glucose　oxidase-labeled　secondary　antibody　as　a　signal　indicator　for　sandwich　-type　immune　conjugation.　In　the　presence　of　the　target　CEA,　the　electrons　and　holes　generated　at　the　surface　of　the　photo　-excited　ultrathin　porous　CuBWO　were　rapidly　consumed　by　the　production　of　H　2　O　2　from　glucose　oxidase　oxidizing　glucose,　resulting　in　a　weakened　photocurrent　signal.　The　photocurrent　intensity　increased　logarithmically　and　linearly　with　increasing　CEA　concentration　(0.02　-50　ng　mL　-1　),　with　a　detection　limit　of　15.0　pg　mL　-1　(S/N　=　3).　The　system　provides　a　broader　idea　for　inferring　the　electron　-hole　transport　mechanism　in　ultrathin　porous　nanosheet　layer　materials　and　developing　efficient　PEC　sensors.