Objective: To evaluate the safety and efficacy of composite sophora colon-soluble capsule (CSCC) in treating ulcerative colitis (UC) of the damp-heat accumulation syndrome pattern (DHAS) and to prepare a basis for a phase Ⅲ clinical trial.Methods: A multi-center,randomized,single-blind,and positive drug parallel-controlled design was adopted.There were 126 patients of UC-DHAS stratified and assigned equally to three groups.Patients in two CSCC treated groups,Groups T1 and T2,were treated orally with high (six capsules,thrice a day) and low (four capsules,thrice a day) doses CSCC,and patients in the control group were treated orally with Mesalazine Enteric-coated Tablets (four tablets,thrice a day),respectively,all for eight weeks.The clinical efficacy and safety of treatments were evaluated through clinical symptom observations and colonoscopic examinations.Results: (1) Full analysis set (FAS) and per-protocol set (PPS) analyses showed the comprehensive curative effect in Groups T1,T2,and the control group,obtaining the values of 85.7%,92.9%,and 71.4% (P=0.330),and 89.5%,92.7%,and 73.2% (P=0.552),respectively,demonstrating no statistical significance among the three groups.(2) FAS and PPS analysis showed the efficacy on membranous lesions in Groups T1,T2,and the control group,obtaining the values of 83.3%,92.9%,and 73.8% (P=0.063),and 86.8%,92.7%,and 75.6% (P=0.070),respectively,showing statistical insignificance among the three groups.(3) FAS analysis showed an efficacy tendency on improving tenesmus (P=0.056).No changes were found in improving the other symptoms,and statistical significance was not shown among the three groups (P>0.05).PPS analysis showed the efficacy on single item symptom in Groups T1,T2,and the control group was not statistically significant among the three groups (P=0.082).Conclusions: The comprehensive effect of CSCC in treating UC is basically equivalent to that of Mesalazine enteric-coated tablet;however,the tendency was shown to improve symptoms.Its efficacy could not be raised by increasing the dosage used.Therefore,the recommended dosage of CSCC is four capsules,three times a day.