〔Abstract〕 Objective To observe the clinical effect of Gegen Qinlian decoction combined with mesalazine in the treatment of ulcerative colitis. Methods A total of 130 patients with ulcerative colitis admitted to Zhengzhou Kai'an Hospital from May 2021 to May 2022 were selected and divided by drawing lots into a control group (65 cases were treated with mesalazine) and an observation group (65 cases were treated with Gegen Qinlian decoction combined with mesalazine). The inflammatory response and recovery of patients in the two groups were compared after different treatments. Results After treatment, the traditional Chinese medicine syndrome scores of the observation group were lower than those of the control group, and the differences were statistically significant (P < 0.05). The levels of inflammation indicators of the observation group were lower than those of the control group after treatment, and the differences were statistically significant (P < 0.05). In terms of various oxidative stress indicators, after treatment, the level of malondialdehyde in the observation group was lower than that in the control group, while the levels of catalase, superoxide dismutase and glutathione peroxidase were higher than those in the control group, with statistical significance (P < 0.05). And there was no statistically significant difference in the occurrence of adverse reactions between the two groups (P > 0.05). Conclusion In the clinical treatment of ulcerative colitis, mesalazine combined with Gegen Qinlian decoction can promote the recovery of symptoms and signs, relieve the inflammatory response of patients and enhance the antioxidant function, with high safety.