Objective Quantitative analysis of hepatic occupying lesions under different b values of ADC, to explore the optimal selection of b value and differential diagnosis of malignant and benign liver lesions of the ADC threshold. Methods 96 cases of hepatic occupying lesions were examined by Siemens 3.0T MR-DWI, b value were set as 200, 500, 800s/mm2 . The ADC values of various lesions among different b values were measured respectively and analyzed statistically. Results 1 With the increase of b value, the ADC value of various lesions decreased. The differences of ADC value between the b200 group and the b500, 800 group were statistically significant.And between the b500 and the b800 group, there were no significant difference except for HCC.When the b value was 500, 800s/mm2 , the ADC value obtained relatively stable. 2 In three kinds of b value, the ADC values of hemangioma and the other group lesions were statistically significance while there were no significant differences between malignant tumors, also there were no significant difference between FNH and metastasis.When the b value was 500 or 800s/mm2 , the ADC values of FNH and HCC, cholangiocarcinoma were statistically significance. 3 Taking ROC curve，500s/mm2 was the optimal b value in the diagnosis of hepatic occupying lesions.The best threshold of ADC in the differential diagnosis of benign and malignant lesions was 1.27×10-3mm2 /s, while the sensitivity and specificity were 91.4% and 85.2%. Conclusion Quantitative analysis ADC values in different b values is helpful for the differential diagnosis of liver occupying lesions, which is a useful supplement for conventional MR examination.