Objective: To explore the risk factors of delayed bleeding after endoscopic colorectal polypectomy and to establish a column-line diagram model. Methods: 989 patients who underwent endoscopic resection of colorectal polyps in Ma'anshan People's Hospital from August 2021 to January 2024 were selected and divided into a modeling group and a validation group in a 7:3 ratio, with 692 and 297 cases, respectively. Patients were categorized into delayed bleeding and non-delayed bleeding groups according to whether or not delayed bleeding occurred within 14 days after surgery. Risk factors for endoscopic colorectal polypectomy were screened by univariate and binary logistic regression analyses, and the model was validated for differentiation, accuracy, and clinical applicability by subject operating curves(ROCs), calibration curves, decision curve analysis(DCA), and clinical impact curves. Results: The patients in the modeling group, 48 patients(6.9%) experienced delayed bleeding, and the patients in the validation group, 21 patients(7.1%) experienced delayed bleeding. Independent risk factors for bleeding included increased age(OR=1.087, 95%CI:1.061-1.114), larger maximum diameter of polyp base(OR=1.641, 95% CI:1.459-1.846), comorbid hypertension(OR=2.087, 95%CI:1.087-4.008), and the number of polyps removed in a single session>2(OR=2.488, 95% CI:1.121-5.523).ROC curve analysis showed that the AUC of the column-line graph model predicting delayed postoperative hemorrhage was 0.924(95%CI:0.892-0.956) in the modeling group and 0.909(95%CI:0.870-0.947) in the validation group. Calibration curve analysis showed a high degree of agreement between the model predicted and actual probabilities.DCA and clinical impact curve analysis showed that the net clinical benefit was greater than 0 for all ranges of the threshold probability values, and the column-line diagram model predicted delayed postoperative hemorrhage in general agreement with the actual. Conclusion: Patient age, maximum diameter of polyp base, hypertension and number of polyps removed in a single operation are closely related to postoperative delayed hemorrhage after endoscopic colorectal polypectomy, and the column-line diagram model based on the above factors can provide a reference for the identification of high-risk patients, which is of some clinical applicability.