Abstract： Objective To discuss the diagnostic value of intravoxel incoherent motion(IVIM)DWI in the inflammation activity of chronic hepatitis B. Methods One hundred and seventy-five patients with chronic hepatitis B were prospectively collected as inflammation group, and 15 healthy volunteers with no history of hepatitis and normal liver function as control group.All subjects were performed MR plan scans for liver and IVIM tests.The liver apparent diffusion coefficient(ADC),the diffusion coefficient of the true water molecule (D), microcirculation perfusion coefficient (D*) and perfusion fraction (f) were measured. After MRI examination, the inflammation group received liver biopsy within two days, and obtained the pathological hepatitis activity grades.According to the degree of inflammation activity(G),the inflammation group was divided into G1,G2 and G3+G4 groups.The independent sample t test was used for the parameter values between the inflammation group and the control group.A single factor variance analysis was used to compare the parameters among different levels of inflammation group. Spearman correlation analysis was used to evaluate the correlation between inflammation activity grades and IVIM parameters.ROC curve was used to evaluate each parameter in the diagnosis of hepatitis activity pathology classification efficiency.Results The values of ADC, D, D*, f between control group and inflammation group were statistically significant(P<0.05).The results of pathological puncture showed that there were 61 cases of G1,62 cases of G2 level and 52 cases of G3+G4.The ADC,D*and f values in the G1,G2,G3+G4 groups decreased with the increase of the level of inflammation activity, and the difference was statistically significant (P<0.05). There was no statistically significant difference between D values (P>0.05). ADC, D* and f values were correlated negatively with low,moderate and low levels of inflammation activity(r=-0.377,-0.434,-0.226, P<0.05).There was no correlation between D value and inflammation activity(r=-0.076,P>0.05).Areas of ADC,D*and ADC combined with D*values under ROC curves to diagnose≥G2 grade inflammation activity were 0.732, 0.748, 0.837 respectively. Areas of f values under ROC curve to diagnose ≥G3+G4 grade inflammation activity was 0.600.Conclusion ADC and D*values help to identify≥G2 grade inflammation activity,and ADC combined with D*value has the highest diagnostic performance,and has certain reference value for clinical treatment.