Abstract: Neurofilament light chain protein (NfL) is a biomarker that can reflect nerve injury and disease, which is used for the detection of Alzheimer's disease (AD). Its detection is of great significance for the early diagnosis and prevention of AD. In this study, the COF-LZU1@CNT-COOH composite was synthesized by combining highly stable imine COFs, COF-LZU1, with carboxylated carbon nanotubes, and was used to construct an electrochemical immunosensor for the detection of neurofilament protein light chain (NfL). Under the optimized conditions, the constructed NfL electrochemical immunosensor had good stability, reproducibility and selectivity.The detection range is 0.05 pg/mL to 0.5 ng/mL, with a detection limit of 0.017 pg/mL. Two-dimensional imine COFs are highly advantageous for immobilizing antibodies on modified electrode surfaces due to its large conjugated structure and abundant pore channels on the two-dimensional plane. Meanwhile, CNT-COOH increased its conductivity and amplified the obtained electrical signal, thereby reducing the detection limit of the electrochemical immunosensor.