Abstract: ob＜x＞jective To investigate the diagnostic value of 3.0T MRI different sequence features and parameters for high and low grade clear cell renalcarcinoma (ccRCC). Methods from January 2012 to April 2020, 89 patients with ccRCC proven by surgical pathology in The Affiliated Hospital Of Xu Zhou Medical University were enrolled. The pathological and MRI data of these patients were retrospectively analyzed, including preoperative renal MRI and enhanced contrast MRI. According to the Fuhrman nuclear grade system, all ccRCCs were divided into 70 cases in low grade(gradeⅠ,Ⅱ) group and 19 cases in high grade group (gradeⅢ,Ⅳ). The occurrence rates of pseudocapsule, cystic degeneration, necrosis, hemorrhage, calcification and fibrous cord , vein thrombosis,renal sinus and pefinephfic invasion, lymphadenopathy, and me＜x＞tastasis were statistically analyzed. The difference in DWI signal intensity of the lesion, the enhancement degree and method were Recorded. The maximum diameter of tumor and the apparent diffusion coefficient value (ADC value) were also measured. Two-sample t-test, Chi-squared test and Receiver operating curve (ROC) were used to evaluate the MRI date between two groups . Results In the MRI image signs, There were statistically significant differences in the maximum tumor diameter, necrosis, vein thrombosis, renal sinus and pefinephfic invasion, lymphadenopathy, me＜x＞tastasis, DWI signal intensity, and medullary phase enhancement between the high and low grade groups (t= -4.508, (2 = 4.625, 10.507, 7.870, 31.861, 6.874, 15.894, 11.421, all P <0.05), the corresponding areas under the curve(AUC) were: 0.816, 0.638, 0.692, 0.665, 0.737, 0.658 0.752, 0.661. The differences between cystic degeneration, hemorrhage, calcified cord, pseudocapsule, and enhancement mode was not statistically significant between the two groups ((2= 0.381, 1.153, 0.132, 3.009, 3.168, all P> 0.05). The ADC value of the low grade group is (1.92 + 0.03) × 10-3mm2 / s, which is significantly higher than the ADC value of the high grade group (1.61 + 0.04 )× 10-3mm2/ s, (t = 4.89, P <0.05), and the AUC was 0.830. Among the different diagnostic combinations, the AUC of the combination of ADC value, tumor maximum diameter, and medullary phase enhancement was 0.902, and the sensitivity was 73.7%, specificity was 92.2%. Conclusion Qualitative and quantitative analysis of multimodal MRI can differentiate and diagnose high and low grade ccRCC. The ADC value combined with the maximum diameter and the enhancement degree were the most effective in the diagnosis of high grade ccRCC, which can provide a reference for the clinic.