Objective： To observe the clinical effect and safety of modified Shaoyao tang combined with ozone rectal perfusion for ulcerative colitis(UC)with large intestine damp-heat syndrome.Methods：Divided 74 UC patients with large intestine damp-heat syndrome into the treatment group and the control group randomly according to random number table method，37 cases in each group.Both groups receivedmesalazine enteric-coated tablets for treatment，while the treatment group additionally received modified Shaoyao tang combined with ozone rectal perfusion.One course of treatment lasted for 30 days.Evaluated the curative effect of the two therapies on Chinese medicine syndrome and mucosal lesions.Observed change of scores of Sutherland disease activity index before and after treatment.Results：The effect on Chinese medicine syndrome in the treatment group was better than that in the control group，the difference being significant(Z=-2.038，P=0.042).The effect on mucosal lesions in the treatment group was better than that in the control group，the difference being significant(Z=-2.011，P=0.044).Before treatment，compared scores of Sutherland disease activity index in both groups，there was no significant difference(P＞0.05).After treatment，scores of Sutherland disease activity index in both groups were lower than those before treatment，differences being significant(P＜0.01)；decrease of the index scores in the treatment group was more evident than that in the control group，difference being significant(P＜0.05).No obvious adverse reaction was found in both groups during the treatment.Conclusion：On the basis of mesalazine enteric-coated tablets，applying modified Shaoyao tang combined with ozone rectal perfusion for UC patients with large intestine damp-heat syndrome can effectively improve symptoms and body signs of patients as well as enhance the curative effect with high safety.