Purpose: To assess the preoperative risk factors for postoperative urosepsis after mini-percutaneous nephrolithotomy (mPCNL) in patients with large kidney stones. Methods: Records of 171 patients with large (>= 30 mm) kidney stones who underwent mPCNL from December 2013 to October 2019 were reviewed. Demographic data of patients, preoperative urine analysis, urine culture, and routine blood tests and abdominal computerized cosmography data were collected and analyzed. A predictive nomogram model was established based on the results of logistic regression. Results: Twenty-nine patients (17%) developed postoperative urosepsis in this study. Univariate analysis demonstrated that preoperative urine leukocytes ( p < 0.001), urine nitrite ( p < 0.001), stones in adjacent calices on the coronal plane (p < 0.001), the maximum cross-sectional area of stones ( p < 0.001), the diameter of hydronephrosis (p = 0.010), and number of stones (p = 0.044) were associated with postoperative urosepsis after mPCNL in patients with large kidney stones. And preoperative urine leukocytes >= 450/mu L (p = 0.002) was the only independent risk factor for postoperative urosepsis in multivariate logistic regression analysis. Based on the results of multivariate regression, a nomogram model was established for the prediction of postoperative urosepsis with ideal discrimination (area under receiver operating characteristic curve was 0.867). Conclusion: Patients with certain preoperative characteristics, including higher urine leukocytes, positive urine nitrite, stones in adjacent calices on the coronal plane, larger maximum cross-sectional area of stones, larger diameter of hydronephrosis, and larger number of stones, who received mPCNL may have a higher risk of postoperative urosepsis. A predictive model can help urologists identify patients who may develop postoperative urosepsis with high probability.