Objective To investigate the prevention of diarrhea by oral BIFICO for infants aged 1-6 years.Methods 490 cases of infants were randomly divided after age stratification:the experimental group (n =247) and the control group (n =243).Based on principles of randomized double-blind and placebocontrolled,the infants were given BIFICO(dedicated clinical research)therapy for 4 consecutive days,then observed for 21 days.25 days composed a cycle.They were observed total 5 cycles.During the study period,principles for "the diarrhoea patients must be detected",follow-up visited the participant infants and conducted etiology detection by way of sampling for diarrhea infants.Evaluate the prevention efficacy of diarrhea by oral BIFICO for infants aged 1-6 years.Results A total of 480 completed all study.120 and 95 infants in the control group and experimental group were detected with diarrhea.The incidence of diarrhea was 50.85％ and 38.93％ in these two guoup,respectively.The difference has statistical significance (x2 =4.175,P =0.041).In the third observation period,the infants in the control group had a higer incidence of diarrhea compared with which in the experimental grouP(x2 =4.415,P =0.036).14 strains of rotavirus,3 strains of norovirus,3 strains of sappovirus,2 strains of adenovirus,5 strains of salmonella and 4 strains of Shigella were check out in 128 samples.Conclusion Oral BIFICO can paly certain preventive role on diarrhea,and decrease the incidence of diarrhea in infants aged 1-6 years.