The　development　of　simple,　fast　and　sensitive　aptasensor　for　OTA　plays　an　important　role　in　food　safety　due　to　its　severe　toxicity.　In　this　research,　taking　advantage　of　the　intrinsic　peroxidase-like　activity　of　g-C3N4　nanosheet　(g-CNNS)　and　its　high　affinity　toward　signal-strand　DNA,　a　label-free　electrochemical　OTA　aptasensor　was　fabricated.　There　is　an　outstanding　property　that　the　aptasensor　did　not　require　labeled　aptamer　and　immobilization　of　g-CNNS　compared　with　previous　g-CNNS-based　aptasensors.　The　presence　of　OTA　induced　the　conformational　change　of　the　aptamer,　and　then　g-CNNS　noncovalently　assembled　with　the　free　complementary　strand　on　the　electrode　via　pi-pi　interaction.　The　captured　g-CNNS　catalyzed　the　oxidation　of　H2O2　to　amplify　current　signal.　As　a　result,　this　aptasensor　realized　the　detection　limit　of　0.073　nM,　and　was　also　employed　to　assay　OTA　in　the　real　samples,　including　red　wines,　juices　and　corns.　More　importantly,　the　development　of　this　label-free　electrochemical　aptasensor　opens　up　the　application　of　g-CNNS　as　the　peroxidase-mimicking　DNAzyme.