Abstract: Objective: To investigate the value of computed tomography-based extracellular volume fraction (ECV) for preoperative evaluation of WHO/ISUP pathologic grading of clear cell renal cell carcinoma (ccRCC). Methods: Seventy-two patients with ccRCC who underwent postoperative histological confirmation were retrospectively enrolled. All patients underwent preoperative CT scanning of the abdomen and three-phase enhancement scanning according to the WHO/ISUP grading. Grades I and II were categorized as the low-grade group (48 patients) and grades III and IV were categorized as the high-grade group (19 patients). General clinical data of the two groups were collected, and quantitative parameters, including delayed aortic net value added (∆HU_Aorta ), delayed tumor net value added (∆HU_tumor)and ECV, were measured and compared, and the diagnostic efficacy of ECV in the pathological grading of ccRCC was evaluated by plotting the ROC curve. Results: The ∆HU_tumor and ECV of ccRCC in low-grade group were significantly higher than those in high-grade group (P<0.05). The ROC curves demonstrated that the efficiency of ECV in evaluating WHO/ISUP low-grade ccRCC (AUC: 0.834) was higher than that of ∆HU_tumor(AUC:0.725). Conclusion: CT-based ECV is valuable for the preoperative evaluation of ccRCC pathological grade.