OBJECTIVE： To investigate therapeutic efficacy of bifidobacteria triple viable bacteria combined with infliximab in the treatment of moderate and severe ulcerative colitis （UC）， and its effects on immune function. METHODS： Seventy-two UC patients were selected from gastroenterology department of the First Affiliated Hospital of Chongqing Medical University during Jun. 2009 to Jan. 2015. They was divided into single group and combination group according to therapy plan， with 36 cases in each group. Single group was given infliximab 5 mg/kg， ivgtt， on 0， 2nd， 6th， 8th week. Combination group was additionally given bifidobacteria triple viable bacteria 420 mg， tid. Both groups were treated for consercutive 2 months. Clinical efficacies were compared between 2 groups as well as the levels of humoral immunity and T cell function. The occurrence of ADR was observed in 2 groups. RESULTS： Clinical response rate of combination group was 86.11％， which was significantly higher than 52.78％ of single group， with statistical significance （P＜0.05）. Before treatment， there was no statistical significance in humoral immunity and T cell function between 2 groups （P＞0.05）. After treatment， the levels of CD4+ and CD4+/CD8+ were significantly increased in both 2 groups， while the levels of CD8+， Th1 and Th2 were significantly decreased； the combination group was significantly better than the control group， with statistical significance （P＜0.05）； there was no statistical significance in CD3+ between 2 groups before and after treatment （P＞0.05）. After treatment， the levels of IgA and IgG were increased significantly in 2 groups， and the level of C3 was decreased significantly； the combination group was significantly better than the control group， with statistical significance （P＜0.05）； there was no statistical significance in IgM content and C4 level between 2 groups before and after treatment （P＞0.05）. There was no statistical significance in the incidence of ADR between 2 groups （P＞0.05）. CONCLUSIONS： Bifidobacteria triple viable bacteria combined with infliximab shows significant therapeutic efficacy in the treatment of moderate and severe UC， and can significantly improve humoral immunity function and the recovery of T cell level， with good safety.