Objective To research on phenylketonuria children in low-phenylalanine milk treatment,comparison of breast milk and formula milk on blood phenylalanine values. Methods Children patients who had been diagnosed of phenylketonuria by Neonatal Disease Screening Center of Northwest Women and Children Hospital from January to December 2012 were retrospectively analyzed.The patient were divided into breast feeding group(n=68)and formula milk feeding group(n=20)according to the feeding pattern,and the blood phenylalanine values and the condition of growth and development regulary were observed. Results The mean blood phenylalanine values of 60 patients ( 88.24%) in breast feeding groups were in normal range,however only 13 patients (65.00%)in formula milk feeding groups,the rate was statistically different(χ²=4.372,P＜0.05).The T value of height,weight and intelligence development of two groups were 0.17,2.42 and 2.7,there was no significantly difference(P＞0.05). Conclusion There are different effects between breast feeding group and formula milk feeding group in treatment of patients with phenylketonuria,the breast feeding may contribute to control the blood phenylalanine values of patients with phenylketonuria.