Objective To explore the therapeutic effect and mechanism of Huazhuo Jiedu Prescription in the treatment of ulcerative colitis（UC）.Methods 120 patients with UC were randomly divided into observation group and control group with 60 cases each.The observation group was treated with Huazhuo Jiedu Prescription one bag and twice a day,and the control group was treated with Mesalazide enteric coated tablets 1.0 g each time and 3 times a day.Continuous treatment lasted for 4 weeks as one course in both groups.The improvement of Geboes index,colonoscopy mucosal performance,quality of life score,Mayo activity index,serum inflammatory factors IL-8,IL-35,and coagulation index serum FIB levels before and after treatment were compared, and the recurrence was added up within one year after the treatment finished.Results After the treatment,the Geboes index,Mayo activity index,serum inflammatory factor IL-8 level,and blood coagulation index serum FIB levels in the observation group were lowered more than that before the treatment（P<0.05）.Particularly,Mayo activity index,serum inflammatory factor IL-8 level,and blood coagulation index serum FIB levels in the observation group were lower than that of the control group,quality of life scores,serum inflammatory factor IL-35 Level was higher than that of the control group after the treatment（P<0.05）.Compared with the control group,the improvement of erosion and ulcer in the treatment group was not significant（P>0.05）,and the improvement of intestinal mirror performance such as congested edema and granulomatous changes was better than that of the control group（P<0.05）.The relapse rate was 10.64% in the observation group,and 23.53% in the control group one year after treatment（P<0.05）.Conclusion Huazhuo Jiedu Prescription can improve the clinical symptoms of UC patients,repair the pathological damage of intestinal mucosa and reduce the recurrence rate.The mechanism may be related to the regulation of serum inflammatory factors IL-8,IL-35 and coagulation factor FIB.