Develop an immunoassay method for determination of clenbuterol.A direct competitive chemiluminescent enzyme immunoassay(dc-CLEIA) was developed for determining clenbuterol.The results showed that the optimized assay conditions for both the highest sensitivity and the best stability were as follows: coating antigen concentration was 25 ng / mL,and dilution fold of antibody enzyme conjugate in 0.02 mol / L pH 7.0 PBS dilution was 80 000.The developed method presented an IC 50 of 0.09 ng / mL,a detection limit of 0.01 ng / mL,a linear range of 0.02 to 7.59 ng / mL.Intra-and inter-batch CV relative standard deviations were below 15%.The analytical recovery rate in urea,pork,liver and fodder sample was 94.5%,95.3%,90.7%,94.1%,respectively.A comparison result between HPLC and the developed assay showed better relativity.The method is sensitive and stable,and it indicates that the dc-CLEIA method can be used to analyze sample.