Okadaic　acid　(OA)　biotoxin　acts　a　well-established　inhibitor　of　protein　phosphatase　even　a　tumor　promoter　of　human　being,　arouse　great　attention　in　safety　monitoring.　However,　the　powerful　and　convenient　nanosensing　technologies　for　addressing　the　demands　such　as　rapidity,　high　sensitivity,　and　stability　in　the　in-field　test　of　OA　shellfish　toxin　is　still　scarce.　Herein,　a　high-performance　magnetic　biometric　nanosensor　(MBNS)　integrating　oriented　aptamers　and　ultrasensitive　laser-induced　fluorescence　(LIF)　was　firstly　proposed　for　the　in-field　detection　of　trace　OA　in　seafoods.　High-density　aptamers　hybridized　with　FAM-labeled　cDNA　were　tethered　to　the　surface　of　AuNPs　on　magnetic　MIL-101@Fe3O4,　and　then　finely　regulated　by　mercaptohexyl　alcohol　(MCH)　to　be　orderly　assembled,　as　was　successfully　utilized　to　engineer　an　active　biological　nanosensor　for　highly　specific　recognition　of　OA.　Aptamers　anchored　on　magnetic　Fe3O4@MOF@AuNPs　activate　a　biometric　micro　-reactor　of　OA,　in　which　the　superior　LIF　properties,　conformation　regulation　of　aptamer,　and　the　specific　recognition　using　aptamer　genes　were　adopted.　The　magnetic　nanosensor　with　an　excellent　specificity　and　super　sensitivity　for　OA　analysis　was　achieved　within　20　min.　Moreover,　the　content　of　captured　OA　could　facilely　be　recorded　by　measuring　the　fluorescence　intensity,　and　the　limit　of　detection　(LOD)　and　limit　of　quantitation　of　OA　(LOQ)　reached　0.015　and　0.050　ng/mL　respectively,　which　was　far　better　than　most　aptamer-based　biometric　sensing　methods.　The　feasibility　for　accurate　test　of　trace　OA　toxin　in　the　fortified　shellfish　samples　was　validated　with　the　recovery　yields　of　88.2-107.5%　and　RSD　of　0.5-7.6%,　respectively.　The　result　demonstrated　that　the　oriented-aptamer　encoded　MNS　had　significant　practical　values　in　rapid　and　ultrasensitive　detection　of　OA　biotoxin　and　the　related　safety　applications.