Objective To analyze the risk factors of venous thromboembolism(VTE)after endoscopic surgery in elderly patients with urinary system calculi,construct a prediction model and validate it.Methods A retrospective analysis was conducted on the clinical data of 402 elderly patients(≥ 60 years)with urinary system calculi who underwent endoscopic surgery in our hospital during Jan.2018 and Jan.2023.The patients were divided into VTE group(n=43)and non-VTE group(n=359)based on whether VTE occurred after surgery.Risk factors of VTE were screened with univariate and multivariate logistic regression analyses.Based on the screening results(P＜0.05 for the factor),a nomogram prediction model was established,the receiver operating characteristic(ROC)curve was drawn,the area under the curve(AUC)was calculated to determine the efficacy of the model,and a calibration chart was drawn to determine the accuracy of the model.Results Univariate analysis showed that age＞70 years,body mass index(BMI)≥30,VTE history,history of malignant tumors,diabetes,operation time＞180 min,diuretic use during operation,and postoperative ambulation time＞24 h were risk factors of VTE(P＜0.05).Logistic regression analysis showed that age＞70 years,BMI ≥ 30,history of VTE,history of malignant tumors,and operation time＞180 min were independent risk factors of VTE(P＜0.05).The AUC in the ROC curve of the validation set data was 0.789(95％CI:0.731-0.848,P＜0.001).The calibration chart showed that the calibration curve was close to the standard curve(Brier=0.13).Conclusion Age＞70 years,BMI ≥30,history of VTE,history of malignant tumors,and surgery time＞180 min are independent risk factors of postoperative VTE in elderly patients with urinary system calculi undergoing endoscopic surgery.The prediction model can effectively predict the risk factors of postoperative VTE.