Phenylketonuria is primarily due to a deficiency of phenylalanine hydroxylase in the body, which leads to the inability of phenylalanine to convert to tyrosine, resulting in the accumulation of phenylalanine and ketones, which are then excreted in the urine, causing a series of clinical symptoms. The main clinical manifestations of phenylketonuria are intellectual disability, psychiatric and neurological symptoms, and urine that smells like mouse. The treatment of phenylketonuria mainly involves a low-phenylalanine diet, maintaining the concentration of phenylalanine within a certain range. Therefore, the diet generally should not include foods high in phenylalanine concentration. At the same time, it is necessary to monitor the concentration of phenylalanine in the blood, as levels that are too high or too low are detrimental to a baby's growth and development. Treatment generally includes feeding with specialized low-phenylalanine formula, and during childhood, food intake can include starches, vegetables, fruits, and other low-protein foods, so it is important to consume high-protein foods sparingly.