Objective: To evaluate the risk factors of postoperative upgrade to pT₃a of cT₁ renal cell carcinoma, and to establish a nomogram prediction model to improve the ability of predicting locally advanced renal cell carcinoma and provide a reference for clinical surgical decision-making. Methods: Clinical data of 1 376 patients with cT₁ (diameter ≤ 7 cm) renal tumor hospitalized for surgery from January 2010 to December 2016 were retrospectively analyzed. There were 979 males and 397 females, with the mean age of (57.65±10.92) years. The mean body mass index (BMI) was (25.47±3.27) kg/m² and the average tumor size was (4.02±1.52) cm. There were 711 tumors on the left and 665 on the right. There were 363 cases with clinical symptoms, 567 patients with smoking history , 732 cases with history of chronic disease. There were 289 cases with tumor necrosis, 636 cases with tumor protrusion, 822 cases with irregular tumor , and 738 cases with renal sinus compression. Partial nephrectomy and radical nephrectomy were performed in 396 cases and 980 cases respectively. Mann-whitney U test and chi-square test were used for univariate analysis, logistic regression analysis was used for multivariate analysis to analyze the predictors of upgrading, R software was used to construct the nomogram predictive model, C-index was used to evaluate the model discrimination, and calibration curve method was used to evaluate the consistency of the model. Results: Postoperative pathology of total 1 376 cases showed that there were 1 195 cases of clear cell carcinoma of kidney, 48 cases of papillary cell carcinoma, 57 cases of chromophobe cell carcinoma, and 76 cases of other types. Among the 1 376 patients with cT₁ renal tumor, 75 patients were upgraded to pT_3a, accounting for 5.5% of all patients. Univariate analysis showed that the patients who upgraded to pT_3a were older [(63.08±10.17) years old and (57.34±10.88) years old], and the tumor length and diameter were larger [(5.24±1.35) cm and (3.95±1.51) cm]. Patients with clinical symptoms [46.7% (35/75) vs. 25.2%(328/1 301)], patients with CT indication of tumor necrosis [40.0%(30/25 975) vs. 19.9% (259/1 301)], patients with irregular tumor contour [73.3%(55/76 775) vs. 59.0%(767/1 301)], and patients with radical nephrectomy were higher [(92.1% (70/91 075) vs. 70%(910/1 301)]. All the differences were statistically significant (P<0.01). Multivariate analysis showed that the independent predictors of upgrading were age (OR=1.046, P<0.001), larger tumor (OR=1.504, P<0.001), clinically symptom (OR=2.153, P=0.004), irregular tumor profile (OR=2.466, P=0.002), and tumor necrosis on CT (OR=2.588, P<0.001). The C-index was 0.808, the calibration curve of forecasting curve with the standard curve fit was good, and the prediction of renal cancer are better in predict consistency. Conclusions Based on the five preoperative predictors, including age, tumor size, clinical presence or absence of symptoms, tumor profile, and whether or not the tumor necrosis indicated by CT, this study developed a nomogram of cT₁ renal cancer upgrade to pT_3a. This nomogram has a good statistical significance, and this model can provide prognosis consultation for patients and provide reference for doctors to make decisions before treatment.