Objective:To explore the effect of moxibustion for preventing post-hemorrhoidectomy urinary retention of mixed hemorrhoids.Design:Two-arm randomized clinical trial with blinded outcome assessment and statistician.Setting:Anorectal Department of Changshu Affiliated Hospital of Nanjing University of Chinese Medicine,from October 2020 to a cutoff day in March 2021.Participants:120 patients with mixed hemorrhoids undertaken hemorrhoidectomy.Interventions:In the moxibustion group,moxibustion was exerted after surgery at Zhongji(CV3),Qihai(CV6),Guanyuan(CV4)and Sanyinjiao(SP6,bilateral).In the medication group,tamsulosin was administered orally after surgery.The cases were all observed for 24 h in two groups.Outcome measures:The primary outcome was incidence of post-hemorrhoidectomy urinary retention and the secondary outcomes included time to the first voiding,the first voiding volume and adverse events were measured and compared between two groups.Results:Sixty patients in each group were included in the data analysis and no change was made to the design of the trial after the trial begun.After treatment,the incidence of the post-hemorrhoidectomy urinary retention was 5%in the moxibustion group,lower than 20%in the medication group(P<0.05).The time to the first voiding after surgery was(4.76±1.69)h in the moxibustion group,shorter than(6.81±1.15)h in the medication group(P<0.05).The first voiding volume in the moxibustion group was(300.67±110.33)mL,higher than(224.67±90.88)mL in the medication group(P<0.05).There was no adverse event during study in the moxibustion group.Dizziness and nausea occurred in the medication group.Conclusion:Moxibustion reduced the incidence of post-hemorrhoidectomy urinary retention,shortened the time to the first voiding and improved the urine volume after hemorrhoidectomy of mixed hemorroids.This therapy could be beneficial and safe,and thus could be recommended to the clinical practice.