A　photoelectrochemical　(PEC)　aptasensing　platform　is　devised　for　sensitive　detection　of　an　organophosphorus　pesticide　based　on　dissolution　of　core-shell　MnO2　nanoflower@CdS　(MnO2　NF@CdS)　by　thiocholine　(TCh).　TCH　is　produced　from　the　butyrylcholinesterase-acetylthiocholine　system,　accompanied　by　target-triggered　rolling　circle　amplification　(RCA).　The　core-shell　MnO2　NF@CdS　with　excellent　PEC　performance　was　synthesized　and　employed　as　a　photo-sensing　platform.　The　target　was　detected　on　a　functionalized　magnetic　probe　with　the　corresponding　aptamer.　Upon　malathion　introduction,　the　aptamer　was　detached　from　the　magnetic　beads,　while　capture　DNA　(cDNA,　with　primer　fragment)　remained　on　the　beads.　The　primer　fragment　in　cDNA　can　trigger　the　RCA　reaction　to　form　a　long　single-stranded　DNA　(ssDNA).　Furthermore,　a　large　number　of　butyrylcholinesterase　(BChE)　were　assembled　on　the　long　ssDNA　strands　through　the　hybridization　with　the　S-2-Au-BChE　probe.　Thereafter,　TCh　generated　from　hydrolysis　of　ATCh　by　BChE　can　reduce　MnO2　NF　(core)　to　Mn2+　and　release　the　CdS　nanoparticles　(shell)　from　the　platform　electrode,　significantly　enhancing　the　PEC　signal.　Under　optimal　conditions,　the　proposed　aptasensor　exhibited　high　sensitivity　for　malathion　with　a　low　detection　limit　of　0.68　pg　mL(-1).　Meanwhile,　it　also　presents　outstanding　specificity,　reproducibility,　and　stability.　Importantly,　the　sensing　platform　provides　a　new　concept　for　detection　of　pesticide.