Background The routine establishment of a diverting stoma (DS) remains controversial in every patient undergoing Dixon operation. We aimed to establish a model for the risk assessment of rectal anastomotic leak (RAREAL) after Dixon in non-emergency patients with rectal cancer, using routinely available variables, by which surgeons could individualize their approach to DS. Methods 413 patients who underwent Dixon operation for rectal cancer from January 2015 to December 2018 were taken as the model group for retrospective study. Univariate and multivariate logistic regression analysis was used to determine the independent risk factors associated with anastomotic leakage(AL). The area under the curve (AUC) of the receiver operating characteristic (ROC) and the Youden index were used to evaluate the RAREAL score. We constructed the RAREAL model. 191 patients who underwent Dixon operation due to rectal cancer from January 2019 to December 2020 were collected according to the uniform criteria as a validation group to validate the RAREAL model. The RAREAL score was performed on the patients in the modeling group, the ROC curve was used for analysis, and the Z test was used to evaluate the consistency of the ROC curve between the modeling group and the validation group. Results In the model group, multivariate analysis identified the following variables as independent risk factors for AL: HbA1c (odds ratio (OR) = 7.831; P = 0.004), Left colic artery (LCA) non preservation (OR = 7.035; P = 0.003), Tumor distance from the anal margin (TD) (OR = 14.246; P = 0.000). In the model group, the AUC of the ROC for evaluating AL with RAREAL was 0.764, and when RAREAL score = 4.5, its sensitivity, specificity and Youden index were 0.419, 0.995, 0.415, respectively. The AUC was 0.757 in the validation group and its sensitivity and specificity were 0.471 and 0.989, respectively, when RAREAL score = 4.5. Conclusion The RAREAL score can be used to assess the risk of AL after Dixon operation for rectal cancer, and prophylactic DS should be proactively done when the score is greater than 4.5.