Objective To investigate the risk factors and incidence of postoperative urinary retention in benign anal diseases. Methods The medical data of patients who underwent surgery for benign anal diseases in Chengdu Shangjin Nanfu Hospital from December 2017 to December 2018 was collected by consulted the electronic medical record system of the hospital. According to whether the patients had postoperative urinary retention, the medical data were divided into the urinary retention group and the non-urinary retention group. SAS9.4 software was used to statistical analysis the collected medical data to calculate the incidence of postoperative urinary retention in benign anal diseases. Single-factor Logistic regression analysis was used to select the related risk factors, and multi-factor Logistic regression analysis was used to determine the independent risk factors of postoperative urinary retention in benign anal diseases. Results A total of 1870 patients who underwent surgery for benign anal diseases were included in the study. The incidence of postoperative urinary retention was 31.01%. The incidence of postoperative urinary retention was higher in female patients than in male patients (P＜0.05). The incidence of postoperative urinary retention was higher in patients older than 60 years than in patients younger than 60 years (P＜0.05). The incidence of postoperative urinary retention was higher in married patients than in unmarried patients (P＜0.05). The incidence of postoperative urinary retention after acupuncture anesthesia (Yaoshu point anesthesia) in the operating room of ward was lower than general anesthesia, caudal anesthesia and general anesthesia combined with caudal anesthesia (P＜0.05). There was no statistical difference in the incidence of postoperative urinary retention among the last three anesthesia methods (P＞0.05). The incidence of postoperative urinary retention was different in different types of benign anal diseases and the incidence of postoperative urinary retention was the highest in mixed hemorrhoids and the lowest in internal hemorrhoids (P＜0.05). The length of hospital stay in the urinary retention group was (8.8±3.0) days, which was longer than that in the non-urinary retention group (8.4±2.9 days) (P＜0.05). Conclusion Postoperative urinary retention in benign anal diseases is the result of multiple factors. Risk factors were female, age over 60, married, type of disease, general anesthesia, caudal anesthesia, and general anesthesia combined with caudal anesthesia. Female, general anesthesia, caudal anesthesia, and general anesthesia combined with caudal anesthesia were independent risk factors for postoperative urinary retention.