Objective:To investigate the risk factors of low anterior resection syndrome (LARS)after low anterior resection of rectal cancer (Dixon).Methods:This retrospective study was conducted in Peking University First Hospital and Traditional Chinese Medicine Hospital of Shanxi Provice from Jan 2012 to Jun 2019. A cohort of 504 patients with rectal cancer was enrolled in the study. All the patients underwent anterior resection. The relationship between clinical-pathological data were analyzed retrospectively. Univariate analysis using χ 2 test. Logistic regression analysis was used to screen the influencing factors of LARS, and the Nomogram method was used to score each factors. Results:Univariate analysis showed that BMI≥28 kg/m 2(χ 2=9.450, P=0.002), the distance from the lower edge of the tumors to the anus <6 cm (χ 2=12.070, P=0.001), high ligation of the inferior mesenteric artery (IMA) (χ 2=8.279, P=0.004), preoperative neoadjuvant therapy (χ 2=11.230, P=0.001), postoperative anastomotic leakage (χ 2=11.840, P=0.001) were associated with severe LARS.Multivariate analysis showed that the distance from the lower edge of the tumors to the anus <6 cm ( OR=1.861, 95% CI: 1.289-2.688, P=0.001), BMI≥28 kg/m 2 ( OR=1.747, 95% CI: 1.022-2.987, P=0.041), high IMA ligation ( OR=1.688, 95% CI: 1.157-2.463, P=0.007), preoperative neoadjuvant therapy ( OR=2.719, 95% CI: 1.343-5.505, P=0.005) were independent risk factors for LARS. Nomogram model showed that the total factor ranged from 2 to 212, and the corresponding risk rate ranged from 30% to 80%. The patients with higher score have greater risk for severe LARS. The area under the predictive power curve of Nomogram model (AUC) was 0.749 (95% CI: 0.705-0.793, P<0.001). Conclusion:Lower tumor location, obesity, preoperative neoadjuvant therapy, high IMA ligation and postoperative anastomotic leakage increase the risk of severe LARS.