Objective To investigate the Clinical value of the degree of liver fibrosis and inflammation of hepatitis B by MR-DWI. Methods Admitted to our hospital 102 cases of chronic hepatitis B patients (fibrosis group 74 cases and no fibrosis group 28 cases) and 26 healthy volunteers (control group) underwent MR plain scan and DWI examination,set different b values.Determination of and comparison of different b values each ADC values and different hepatic fibrosis degree and different inflammatory activity of ADC value. Results b values of 100 and 200s/mm2 ,each ADC value difference was not statistically significant (P>0.05);b value of 400,600 and 800s/mm2 ,hepatic fibrosis group,ADC values were significantly lower than those without fibrosis group (P<0.05);b value of 600 and 800s/mm2 ,hepatic fibrosis group S3 and S4 ADC value was significantly lower than that of S0 and S1 (P<0.05);b value is 100,200 and 400s/mm2 ,different liver fibrosis staging ADC values showed no statistical significance (P>0.05);b value of 800s/mm2 ,liver inflammation activity group G4 level ADC value was significantly lower than that of the G1 level (P<0.01),different inflammation activity grade of ADC value differences had no statistical significance (P>0.05). Conclusion DWI in the evaluation of chronic hepatitis B patients with liver fibrosis and inflammation activity degree has a high application value and the ADC values and degrees of hepatic fibrosis and inflammation and necrosis were closely related,the effect is best of b value of 800s/mm2.