The　change　of　surface　charge　density　can　cause　many　changes　in　physical　or　chemical　properties　and　has　been　applied　to　design　many　sensitive　sensors.　Ochratoxin　A　(OTA)　is　a　negatively　charged　target　in　neutral　or　alkaline　solutions.　In　this　work,　a　microchannel-based　electrochemiluminescence　(ECL)　aptasensor　for　OTA　detection　based　on　this　character　had　been　designed.　The　charged　target　directly　combined　with　functionalization　layers　of　the　microchannels,　which　caused　surface　charge　density　variation　and　therefore　resulted　in　the　change　of　ECL　intensity　of　the　(1,10-phenanthroline)ruthenium(II)/tripropylamine　system.　The　decrease　of　ECL　intensity　is　linearly　dependent　on　OTA　concentration　ranging　from　0.5　to　4　ng　mL–1　with　a　detection　limit　down　to　0.17　ng　mL–1.　This　strategy　has　the　advantages　of　simple　interface　chemistry　design　and　universality,　which　offers　a　guiding　significance　for　the　charged　target　assay.　©　2021　American　Chemical　Society