Objective To evaluate the feasibility of T2 *mapping T2 *value combined with DWI ADC value in quantitative assessment of the activity of sacroiliitis.Methods 30 patients diagnosed with ankylosing spondylitis (AS)were divided into 2 groups as acute group (n=17)and chronic group (n=13)according to the BASDAI scores of the clinical severity of disease.And 20 healthy adults were recruited as control group.All groups were examined by MR with traditional sequence,T2 *mapping and DWI in the sacroiliac joint.The T2 *value and ADC value of the bone marrow edema region and normal region were measured.Furthermore,the imaging data and the clinical scores were statistical analysis and compared among three groups.Results T2 *values and ADC values in acute group of AS patients were higher than chronic group (P<0.05),as well as compared with healthy volunteers (P<0.05).There was no statistically significant difference between the chronic group of AS patients and control group (P>0.05).Positive correlation between ADC value and BASDAI was observed in patients group.Conclusion T2 *mapping combined with DWI imaging in AS is beneficial for early diagnosis and quantitative analysis of the activity of sacroiliitis.