Description: Purpose To evaluate the correlation of CT perfusion parameters with the Fuhrman grade in pT1b (4–7 cm) renal cell carcinoma (RCC). Methods CT perfusion imaging and Fuhrman pathological grading of pT1b RCC were performed in 48 patients (10 grade 1, 27 grade 2, 9 grade 3, and 2 grade 4). Equivalent blood volume ( BV Equiv ), permeability surface area product (PS), and blood flow (BF) of tumors were measured. Grade 1 and 2 were defined as low-grade group ( n  = 37), meanwhile high-grade group ( n  = 11) included grade 3 and 4. Comparisons of CT perfusion parameters and tumor size of the two different groups were performed. Correlations between CT perfusion parameters, Fuhrman grade (grade 1, 2, 3, and 4), and tumor size were assessed. Results PS was significantly lower in high grade than in low-grade pT1b RCC ( P  = 0.004). However, no significant differences were found in BV Equiv and BF between the two groups ( P  〉 0.05 for both). The optimal threshold value, sensitivity, specificity, and the area under the ROC curve for distinguishing the two groups using PS were 68.8 mL/100 g/min, 0.7, 0.8, and 0.8, respectively. Negative significant correlation was observed between PS and Fuhrman grade ( r  = −0.338, P  = 0.019). Conclusions The PS of pT1b RCC had negative significant correlation with Fuhrman grade. CT perfusion appeared to be a non-invasive means to predict high Fuhrman grade of pT1b RCC preoperatively and guide the optimal treatment for the patient.