It can be detected by the following methods: 1) puncture test or blood allergen screening test, and also by patch test or eosinophil count; 2) diagnostic avoidance test: children suspected of milk protein allergy, remove milk and products from complementary foods, and if the child’s symptoms improve, it can be judged as milk protein allergy; 3) food stimulation test: if the baby’s symptoms worsen after eating products containing milk protein, it means milk protein allergy.