Objective: To explore the prognostic value of preoperative platelet parameters in locally advanced renal cell carcinoma for the risk stratification of such patients. Methods: Clinical data of patients with locally advanced renal cell carcinoma in the Third Hospital of Peking University from January 2015 to December 2017 were collected. The patients were divided into progression group and progression-free group according to follow-up data, and preoperative platelet parameters and clinical data between the two groups were compared. The optimal cut-off value of platelet parameters was determined by receiver operating characteristic curve (ROC) and analyzed by Kaplan-Meier survival curve. Cox proportional hazards model was used to analyze the independent risk factors of PFS. Time dependent ROC curve, net reclassification index (NRI), and integrated discrimination improvement (IDI) were used to evaluate the improvement of SSIGN model by incorporating platelet parameters. Results: Of the 215 patients, 192 (89.3%) were followed up for a median of 36 months. Sixty-four patients (29.8%) had disease progression during the follow-up, and the median PFS was 46 months. In progression group, the platelet count (PLT) was higher [(250.72 ± 88.59)×10⁹/L vs. (227.27 ± 66.94)×10⁹/L, P=0.042] and the platelet distribution width (PDW) was lower [(12.01 ± 2.27)% vs. (13.31 ± 2.74)%, P = 0.001] than that of progression-free groups. 285×10⁹ /L and 12.65% as the best cut-off values of PLT and PDW, the median PFS of PLT≤285×10⁹ /L group was significantly longer than that of PLT>285×10⁹ /L group (53 months vs. 41 months, P=0.033), and the median PFS of PDW>12.65% group was also significantly longer than that of PDW≤12.65% group (56 months vs. 41 months, P<0.001). Multivariate analysis showed that preoperative PDW (HR=0.735, P<0.001), nuclear grade Ⅲ to Ⅳ (HR=2.425, P=0.001) and sarcomatoid differentiation (HR=3.101, P=0.008) were independent risk factors for PFS. The area under the curve of PDW combined with SSIGN model was larger than that with the original SSIGN model [0.748 (95%CI:0.662-0.833) vs. 0.678 (95%CI: 0.583-0.773), P=0.193], NRI was 0.262 (P=0.04), and IDI was 0.085 (P=0.01), indicating that the predictive ability of PDW combined with SSIGN model was improved. Conclusion: Preoperative high PLT and low PDW are associated with adverse prognosis of locally advanced renal cell carcinoma, and PDW is an independent risk factor. Therefore, preoperative PDW could serve as biomarker for risk stratification of locally advanced renal cell carcinoma.