Objective To evaluate the clinical effect and effect of Mesalazine combined with Saccharomyces boulardii powder on cytokines in patients with ulcerative colitis.Methods Sixty  four patients with ulcerative colitis were randomly divided into combined treatment group ( n=32) and control group ( n=32). Combined treatment group was treated with Mesalazine and Saccharomyces boulardii powder. Control group was treated with Mesalazine only. Clinical efficacy and the drug adverse reaction were compared between the two groups after treatment for 8 weeks.TNF-a and Interleukin10 were tested. Results Compared with control group，combined treatment group induced a significantly increase in the endoscopic score difference before and after treatment（1.51±0.39 vs 0.85±0.32，P＜0.05）.In addition，the total effective rate in combined treatment group（906%，29 cases）was significantly higher than that in control group（688%，22 cases）（P＜0.05）. IL-10 was significantly increased and TNF-a was significantly reduced after treatment in two groups (P＜O．05). IL-10 was more significantly increased and TNF-a was more significantly reduced in observation group (P＜O．05)．Adverse reaction in two groups had no significant difference (P＞0. 05 ). Conclusion The combined treatment with Mesalazine and Saccharomyces boulardii powder is safer and more effective than mesalazine alone for treating ulcerative colitis patients, which can regulate cytokines．