Objective To explore the application effect of electric suction device combined with homemade double-tube continuous irrigation in the treatment of anastomotic fistula after rectal cancer resection with preservation of anal canal. Methods A total of 105 patients who developed anastomotic fistula after sphincter-preserving rectal cancer resection at Jiangxi Provincial People’s Hospital (The First Affiliated Hospital of Nanchang Medical College) from June 2020 to December 2025 were enrolled. They were divided into three groups: group a (electric suction device＋homemade double-lumen tube, n＝30), group b (electric suction device＋conventional double-lumen tube, n＝35), and group c (wall suction device＋conventional double-lumen tube, n＝40). The following parameters were compared among the three groups: continuous irrigation time, hospital stay, total hospitalization cost, fistula healing time, time to normalization of body temperature, granulation tissue growth score, time of inflammatory indicator changes, reoperation rate, and incidence of post-irrigation abdominal bleeding. Results The continuous irrigation time, hospital stay, total hospitalization cost, fistula healing, time for body temperature to return to normal, score for granulation tissue growth, albumin (ALB), procalcitonin (PCT), C-reactive protein (CRP) normalization time in group A were all better than those in group B and group C (all P＜0.05); the reoperation rate in group A was lower than that in group B and group C (P＜0.05); the incidence of abdominal cavity bleeding after irrigation in group A was significantly lower than that in group C (P＜0.05). Conclusion The continuous irrigation and drainage using an electric suction device combined with a homemade double cannula can effectively promote fistula healing, control infection, reduce treatment risks and costs.