Phenylketonuria belongs to a recessive hereditary metabolic disease; how can we take preventive measures? First, we must avoid consanguineous marriages. Second, we need to conduct newborn screening to achieve early diagnosis, early detection, and early treatment. Third, for pregnant women with a family history of this disease, it is mandatory to use DNA analysis or methods like amniotic fluid testing for prenatal diagnosis of their fetuses. Prevention is better than cure. By taking preventive measures early, the chances of complications occurring are greatly reduced. If a baby shows symptoms of newborn phenylketonuria, parents should not take it lightly and should actively cooperate with the treatment.