OBJECTIVE:To systematically review the efficacy of Live combined bacillus subtilis and enterococcus faecium in the prevention and treatment of Antibiotic associated diarrhea(AAD),and provide evidence-based reference for clinical treatment. METHODS:Retrieved from CBM,CJFD and Wanfang database,randomized controlled trials (RCT)of Live combined bacillus subtilis and enterococcus faecium(test group)versus placebo(control group)in the prevention and treatment of AAD. After data ex-tract and quality evaluation,systematical evaluation was performed by using Rev Man 5.0 statistics software. RESULTS:A total of 21 RCT were included,involving 3 881 patients. According to the purpose of different purpose of druguse,the RCT were divided into prevention group and treatment group. Results of Meta-analysis showed the incidence of diarrhea in prevention test group was significantly lower than control group[OR=0.27 ,95% CI(0.22 ,0.32),P<0.001] ,the average hospitalization time in prevention test group was significantly less than control group [MD=-53.19,95%CI(-79.63,-26.75),P<0.001],and the total clinical ef-fective rate in treatment test group was significantly higher than control group[OR=6.76,95%CI(4.16,10.98),P<0.001]. CON-CLUSIONS:The efficacy of Live combined bacillus subtilis and enterococcus faecium are good in the prevention and treatment of AAD. However,due to the limit of methodological quality and sample size,it remains to be further verified with more rigorously designed and long-term follow-up of large-scale RCT.