To establish an indirect ELISA method of β-lactamase detection in milk.MethodsThe Elisa method of Ampicillin was set up and optimized with ampicillin-HRP conjugate and Ampicillin antibody. The method was used to detect the ampicillin in samples and negative control, and β-lactamase was determined indirectly by comparing OD₄₅₀ values. ResultsThe indirect ELISA method for β-lactamase was established, and the sensitivity was 0.0005IU/ml.ConclusionThis method was accurate and reliable, and could be widely applied to detect β-lactamase in milk.