Objective To investigate the method of preparing main components of milk allergens.Methods Isoelectric precipitation,gel chromatography,molecular sieve and other possible methods were used to purify the main allergens in milk.SDS-PAGE was used to identify the purity of protein and double antigen sandwich-ELISA was established to confirm the immunoreactivity of milk allergen.Results Four components of milk allergen,including caseins,β-lactoglobulin,α-lactoalbumin and several macromolecule proteins(P1),were separated and purified by the methods established in this study,and all these components can react with positive serums,whereas β-lactoglobulin and P1 components showed higher immunoreactivity.Conclusion A simple and practical method for preparing milk allergens was found in this study;β-lactoglobulin and P1 components were considered to be the main allergen components in milk.