Objective To investigate the effect of anal fissure excision bandage flap operation on anal function in patients with old anal fissure. Methods The data of 120 patients with old anal fissure who were admitted to our hospital from May 2017 to September 2018 were collected for retrospective analysis. They were divided into control group (58 cases) and research group (62 cases) according to the random number method. The control group received lateral sphincter incision. The patients in the study group underwent treatment of anal fissure excision bandage flap operation. The clinical indicators, anal function and complications were compared between the two groups. Results The healing time and hospitalization time of the study group were lower than that of the control group, and the operation time was higher than that of the control group (P<0.05). Compared with the preoperative period, 1 week after surgery, 1 month after surgery, and half a year after surgery, the Wexner scores of the two groups showed a significant decrease, and the study group was lower than the control group (P<0.05). The incidence of complications such as blood in the stool, urinary retention, anal pain, anal edema, wound infection and anal incontinence were lower in the study group than in the control group (P<0.05). Conclusion Anal fissure excision bandage flap operation for the treatment of old anal fissure is effective, which may improve anal function and reduce complications. It is worthy of clinical promotion.