Objective To study the relationship between the characteristics of diffuse weighted imaging of renal cell carcinoma(RCC) and renal angiomyolipomas(RAML) with minimal fat and the surface diffusion coefficient (ADC) of the lesions. Methods A total of 30 cases of RAML patients with complete MRI examination data were set as observation group, and another 30 patients with RCC were set as the control group from February 2014 to July2016 in our Hospital. The patients' basic information, DWI signal characteristics and ADC values were respectively compared between the two groups. Results The age of the observation group was (47.5+6.2) years, which was significantly lower than that of the control group (63.4+7.3) years old, and the difference was statistically significant (P<0.05). The characteristics of the DWI signal in the observation group were low and slightly high, while the DWI signal in the control group was unevenly high. The observation group ADC=(1.622+0.183)×10-3mm2 /s, significantly higher than the control group (1.454+0.282)×10-3mm2 /s, the difference was statistically significant(P<0.05). Conclusion The value of ADC can be used as a new index for clinical diagnosis of RAML with minimal fat and renal cancer. It is of high application value.