Abstract: Objective To analyze the independent risk factors for diabetic nephropathy （DN） in obese patients with type 2 diabetes mellitus （T2DM）, and to construct and validate a nomogram-based assessment model for the risk of DN in obese T2DM patients. Methods 370 obese T2DM patients treated at the Department of Endocrinology and Metabolic Diseases, the Third Affiliated Hospital of Sun Yat-sen University between January 2021 and December 2023 were retrospectively enrolled. According to urinary albumin/creatinine ratio （ACR）, all patients were categorized into the DN （n = 79） and non-DN （n = 291） cohorts, and then randomly allocated into the training （70%, n = 259） and validation （30%, n = 111） groups. Comprehensive clinical data including laboratory parameters and comorbidities were collected. Variable selection was optimized using LASSO regression, and a nomogram assessment model was constructed based on multivariate Logistic regression analysis. The discriminatory performance, calibration accuracy, and clinical applicability of the model were assessed utilizing the receiver operating characteristic （ROC） curve, Hosmer-Lemeshow （H-L） test, and decision curve analysis （DCA）, respectively. Results Significant intergroup differences were observed in age, duration of diabetes, hypertension, hyperlipidemia, osteoporosis, cerebral infarction, coronary artery disease, systolic blood pressure, waist circumference, alanine aminotransferase （ALT）, aspartate aminotransferase （AST）, albumin （ALB）, blood urea nitrogen （BUN）, creatinine （Cr）, and cystatin C （CysC） （all P < 0.05）. LASSO regression identified seven candidate factors, and multivariate Logistic regression confirmed that duration of diabetes （OR=1.174, 95% CI=1.098-1.265）, hypertension （OR=10.332, 95% CI=3.941-31.499）, ALB （OR=0.840, 95% CI=0.752-0.931）, and Cr （OR=1.016, 95% CI=1.005-1.029） as significant influencing factors for DN （all P < 0.05）. Based on these findings, a nomogram assessment model was constructed. The nomogram demonstrated excellent discrimination： the area under the ROC curve （AUC）=0.913 （95% CI=0.871-0.955） in the training cohort, and AUC=0.919 （95% CI=0.856-0.982） in the validation cohort. H-L goodness-of-fit tests indicated satisfactory calibration in both cohorts （training set： χ ²= 4.048, P = 0.853； validation set： χ ²=6.162, P = 0.629）. Conclusion Duration of diabetes, hypertension, serum Cr, and ALB levels constitute significant influencing factors for DN development in obese T2DM patients. The validated nomogram incorporating these four parameters provides clinically applicable risk stratification for this population.