Abstract: Objective To evaluate the effects of probiotic for preventingpediatricdiarrhea.Methods Original randomized controlled trials (RCTs) which focus on the effects of probiotic for preventing pediatric diarrheawere systematically searched in the Pubmed, Embase, Clinical Trials. gov, and Cochrane Library. The pooled relative risk (RR) of probiotic for preventing pediatric diarrhea against placebo was calculated using random-effects model. Funnel plot and Egger's test were used to detect potential publication bias. I² was used to evaluate the heterogeneity betweenincluded studies. Subgroup analyses were used to explore the effects of probiotic for preventing antibiotic-associated diarrhea, Clostridium difficile-associated diarrhea, and rotavirus diarrhea among children.Results A total of 20 RCTs were included. A total of 1977 children received prophylactic probiotic treatment, while 1947 children received placebo or other treatments. After pooling RRs from included studies, compared with placebo and other treatments, probiotic treatment could significantly reduce 51% diarrhea (RR:0. 49, 95% confidential intervals (CIs):0. 39-0. 62, P< 0. 001). The antibiotic-associated diarrhea significantly decreased 59% (RR:0. 41, 95% CI:0. 29-0. 59, P< 0. 001). And Clostridium difficile-associated diarrheaand rotavirus diarrhea decreased 66% (RR:0. 34, 95% CI:0. 15-0. 76, P=0. 008) and 37% (RR:0. 63, 95% CI:0. 43-0. 92, P=0. 016), respectively.Conclusions Probiotic treatment could significantly reduce pediatric diarrhea, especially for antibiotic-associated diarrhea, including Clostridium difficile-associated diarrheaand rotavirus diarrhea.