Cow’s milk is rich in protein, fat, and other high-quality nutrients, which is an important nutritional source for infants. On the other hand, milk protein is the main factor inducing food allergy in infants and young children. In this study, five kinds of commercially available infant milk powder were selected for static digestion in vitro. The digestive stability of proteins in the five kinds of milk powder was analyzed by electrophoresis and degree of hydrolysis measurement. An enzyme-linked immunosorbent assay (ELISA) was used to evaluate the antigenicity of whey protein in milk powder. The results showed that α-lactalbumin and β-lactoglobulin showed good digestive stability in samples 1, 2, and 4. After gastrointestinal digestion, the antigenicity of α-lactalbumin and β-lactoglobulin decreased in sample 1 but increased in sample 2. The antigenicity of α-lactalbumin increased, while that of β-lactoglobulin decreased in sample 4. Both allergens had lower digestion stability in sample 3 and 5. The antigenicity of α-lactalbumin and β-lactoglobulin increased in sample 5. The antigenicity of α-lactalbumin increased while that of β-lactoglobulin decreased in sample 3.