Objective To investigate the status of lactose intolerance among infants in Qinhuai District of Nanjing and the effects of different interventions,and to provid reference for fargeted inventions. Methods Healthy infants and diarrhea infants were tested by urinary galactose detection separately.Positive test results indicated lactase deficiency,which combined with gastrointestinal symptoms were suggested as lactose intolerance.Then analyze the different intervention results for the lactose intolerant infants. Results The incidence of lactase deficiency in infants with diarrhea was significantly higher than that of healthy children,the incidence of lactase deficiency in breast-fed infants with diarrhea was lower than that of formula-fed infants with diarrhea,the statistical differences of the two aspects were both significant(P＜0.05).The antidiarrheal time of the original milk diet plus lactase group and the lactose-free diet group were less than that of the continued original milk diet group.The differences between the former two and the latter group were significant respectively (P＜0.05).The former two had no statistical difference(P＞0.05). Conclusions Infants with diarrhea are prone to secondary lactose intolerance.The incidence of lactose intolerance in breast-fed infants is lower than that of formula-fed infants.The effects of keeping the original milk diet with lactase and the lactose-free diet to intervene the disease are both better than that of continuing the original milk diet,but has shortcomings in clinical application.Lactose intolerance impairs children's health,so early detection,early diagnosis and early targeted interventions are necessary.