Objective: Cow's milk allergy(CMA) is the most common type of food allergy in infants and young children. Infants with milk allergy need to use low-allergenic hydrolyzed cow milk protein formula for the prevention and management. Although protein allergen levels can be reduced through enzymatic hydrolysis， depending on the type of enzymes used and the various filtering methods， residual antigenic epitopes can still cause food allergies. Therefore， the purpose of this work was to develop a quick and accurate method to assess the immunoreactivity of hydrolyzed cow's milk protein infant formula powder. Methods: Firstly， a direct dot-immunobinding blot assay was used to gauge the samples' immunoreactivity with serum samples from allergic children. Subsequently， an indirect competitive dot-immunobinding blot assay was utilized， using commercially available unhydrolyzed whole protein milk powder as a positive control and other milk product samples as competitive antigens， to evaluate the binding capacity of hydrolyzed milk protein infant powder to serum immunoglobulin E (IgE). Finally， direct， and indirect competitive enzyme-linked immunosorbent assay (ELISA) were also used to validate and confirm the results. Results: The study's findings demonstrated that partially hydrolyzed formula can still bind IgE to induce allergic reactions， while extensively hydrolyzed formula is not immunoreactive. This study provides a new approach for the preliminarily evaluation of the allergenicity of milk protein products using limited serum samples from infants and young children with allergies.