Abstract： Objective:To investigate the effect of pelvic peritoneum reconstruction on the prognosis of patients underwent laparoscopic low anterior resection of rectal adenocarcinoma.Methods:This retrospective cohort study included 97 patients who underwent laparoscopic low anterior resection of rectal adenocarcinoma in General Surgery Department, the First Affiliated Hospital of Soochow University from January 2017 to June 2021. According to the implementation of pelvic peritoneum reconstruction, the subjects were divided into study group (48 patients underwent pelvic peritoneum reconstruction after laparoscopic resection) and control group (49 patients not underwent pelvic peritoneum reconstruction). The two groups were compared in terms of Wexner score of anal function, anorectal manometry results, normal rate of defecation sensation, pelvic floor anatomical structure and postoperative complications. Five-year survival analysis was performed.Results:Patients in the study group and the control group were (61.25±10.38) years old and (59.47±11.40) years old ( P>0.05). The proportions of male patients were 60.4% (29 cases) and 55.1% (27 cases) ( P>0.05) in the study group and control group, respectively. At 3, 6 and 12 months after surgery, Wexner scores of anal function in the study group were lower than those in the control group [(14.29±2.07) vs (16.33±2.18), P<0.001; (9.57±2.34) vs (11.26±2.85), P=0.002; (5.41±1.36) vs (7.86±1.95), P<0.001, respectively]. The anal resting pressure and anal systolic pressure of the study group were higher than those of the control group [(56.29±7.31) mmHg vs (52.88±6.65) mmHg, P=0.018; (129.33±17.36) mmHg vs (110.45±15.22) mmHg, P<0.001, respectively] (1 mmHg=0.133 kPa). The rectal sensory volume, rectal maximum tolerance volume, and the length of anal high-pressure area in the study group were greater than those in the control group [(32.15±4.38) vs (29.76±4.29), P=0.008; (209.57±40.27) vs (184.39±37.56), P=0.002; (3.07±0.52) vs (2.80±0.49), P=0.010, respectively]. At 3 and 6 months after surgery, the normal rates of defecation sensation in the study group were 47.9% (23 cases) and 70.8% (34 cases), respectively, higher than those in the control group [26.5% (13 cases) and 51.0% (25 cases)] ( P=0.029 and 0.046, respectively). The detection rate of intestinal tube accumulation in the study group was lower than that in the control group [12.5% (6 cases) vs 38.9% (19 cases)] ( P=0.003). There was no significant difference in the total incidence of complications (anastomotic leakage, abdominal infection, intestinal obstruction, pendant pneumonia and urinary tract infection) between the two groups [18.8% (9 cases) vs 24.5% (12 cases)] ( P=0.493). There was no significant difference in 5-year cumulative survival rate between the study group and the control group (71.6% vs 68.2%, P=0.309). Conclusion:Pelvic peritoneum reconstruction can improve postoperative anal function and reduce intestinal tube accumulation in patients underwent laparoscopic low anterior resection of rectal adenocarcinoma with high safety and feasibility.