Abstract: Based on HRP-Luminol-H2O2 system, a direct competitive chemiluminescent enzyme immunoassay (DC-CLEIA) was developed for determining Aflatoxin B1.The results showed that the optimized assay conditions for both the highest sensitivity and the best stability were as follows: coating antigen concentration was 0.0625μg /mL, and dilution fold of antigen enzyme conjugate in 0.01mol /L pH7.5 PBST dilution was 10000 fold.The developed method presented an IC 50 of 0.062ng /mL, a detection limit of 0.01ng /mL, a linear range of 0.017⁰.215ng /mL.Intraand inter-batch relative standard deviations (RSD) were below 15%.The analytical recovery in edible oil sample was 88.7% ⁹8%.A comparison result between enzyme-linked immunosorbentassay (ELISA) and the developed assay showed better relativity.The method is sensitive and stable.