Objective To investigate the value of intravoxel incoherent motion diffusion-weighted imaging(IVIM-DWI)and multi-phasic enhanced MRI in the classification of clear cell renal cell carcinoma(ccRCC).Methods The data of 91 patients with pathologically confirmed ccRCC who all underwent multi-phasic enhanced MRI and IVIM-DWI examination were analyzed retrospectively. According to Fuhrman classification criteria,grade Ⅰ - Ⅱ were defined as low-grade group(n=73),grade Ⅲ - Ⅳ were defined as high-grade group(n=18).Mann-Whitney U test,independent sample t test and receiver operating characteristic(ROC)analysis were used for statistical analysis.Results The maximal diameter and pathological stage of ccRCC in the low-grade group were lower than those in the high-grade group,and the differences between the two groups were statistically significant(P<0.001 and P=0.003). The signal intensity and enhancement rate of ccRCC in the high-grade group in corticomedullary phase and parenchyma phase were lower than those in the low-grade group,but there was no significant difference between the two groups(all P>0.05).The ADC and D values of ccRCC in the high-grade group were lower than those in the low-grade group,and the differences between the two groups were statistically significant(P=0.007 and P=0.009).However,there was no significant difference of D *and f between the two groups(P=0.604 and P=0.695).Conclusion Multi-phasic enhanced MRI scanning has a limited value in the classification of ccRCC.IVIM-DWI derived diffusion-related parameters(ADC and D)is of great significance for differentiating between high-grade and low-grade ccRCC.