Abstract: ［Abstract］Objective　To study the impacts of clostridium，montmorillonite powder and mesalazine on Regulative T Cells （Treg）/ Auxilliary T-17 Cells（ Th17 ）immune balance in rats with ulcerative colitis （UC ）induced by 2，4，6 TNBS/ethanol. Methods　48 rats were divided randomly into 6 groups（8 rats per group） including the model，clostridium，montmorillonite，mesalazine，mesalazine plus montmorillonite and normal group. TNBS/ethanol was used to build a model of rats with UC. The quantity of normal saline， clostridium，montmorillonite powder and mesalazine were converted by surface area of rat and given the rats by gastro-tube daily.4 rats were executed on the 5th day after the molded and treatment， Other rats were executed on the 12th day after the molded and treatment，and the blood samples were collected to measure the contents of Treg and Th17 by a flow cytometer and observe the Treg/Th17 ratios．Results（1）The levels of Treg in normal group and the model group were markedly higher than in clostridium，montmorillonite，mesalazine and mesalazine plus montmorillonite group on the fifth day， differences are statistically.（P＜0.05）However， this result reversed dramaticly on the 12th day， which were more lower， especially in clostridium group.Significant difference appeared except the mesalazine group（P＜0.01）；Statistically comparing the 12th day with the 5th day in the treatment， Treg values all rised tremendously ，excluded the normal group and the model group.（2）The level of Th17 in normal group was obviously more lower than in other 5 groups on the 5th and 12th day， apparently more lower than in the model group.The differences have statistic significance（P＜0.05）；Statistically comparing the 12th day with the 5th day in the treatment，the Th17 value decreased apparently in the other 4 groups excluded the montmorillonite and clostridium group，differences were statistically significant（P＜0.05）．（3）The ratio of Treg/Th17 in normal group was obviously more higher than other 5 groups on the 5th and 12th day， apparently higher than in the model group. （P＜0.05）But on the 12th day， the ratios of Treg/Th17 in clostridium，montmorillonite， mesalazine and mesalazine plus montmorillonite group were gradually close to normal group， especially in mesalazine plus montmorillonite group，（P＜0.05）while the model group still keeps lower level，Statistically comparing the 12th day with the fifth day in the treatment，all the ratio of Treg/Th17 rised（P＜0.05）．Conclusions（1）The immune imbalance of Treg/Th17 might play a important role in UC pathogenesis. （2）Clostridium，montmorillonite，and mesalazine could effectively restrain or reduce the level of Th17 and elevate the level of Treg in rats with UC model to prevent inflammatory reaction and shorten the duration of inflammation.