〔Abstract〕 Objective To quantitatively analyze creeping fat in energy spectrum CT to evaluate the activity of Crohn′s disease. Methods A retrospective study was performed on 127 patients with CD who received energy spectrum CT.The activity of CD was assessed by classical clinical CDAI and these patients were divided into remission group, mild-activity group and moderate and severe-activity group.The slope of spectral HU curve(λHU),normalized iodine concentration(NIC) and normalized water concentration(NWC) of the creeping fat in the diseased intestine were measured and calculated.The visceral fat area(VFA) and subcutaneous fat area(SFA) of all patients were measured by CT post-processing workstation.The relationship between these quantitative data and the inflammatory activity of Crohn′s disease was analyzed. Results The λHU、NIC and NWC in moderate and severe CD patients were higher than those in mild CD patients [λHU(-0.49±0.09)vs(-1.24±0.13),P<0.05;NIC(-4.25±0.96) mg/mlvs(-13.39±2.24) mg/ml,P<0.05;NWC(955.72±5.80) mg/ml vs(931.04±30.25) mg/ml,P<0.05].VFA and VFA/SFA in moderate and severe group were also higher than those in mild group [VFA(79.40±3.58)cm2vs(74.24±6.57)cm2,P<0.05;VFA/SFA(1.01±0.05)vs(0.55±0.09),P<0.05],while SFA in moderate and severe group was significantly lower than that in mild group[(75.57±2.52) cm2vs(137.78±18.31) cm2,P<0.05].λHU,NWC and NIC were all positively correlated with CDAI score(whollyP<0.05),and correlation coefficient r of λHu was 0.881(P<0.001). The AUC of λHU,NIC,NWC and VFA/SFA were respectively 0.957(95%CI:0.922～0.993),0.926(95%CI:0.876～0.977),0.856(95%CI:0.776～0.936),0.793(95%CI:0.699～0.879) in the ROC curve of diagnosing moderate and severe group. Conclusion Energy spectrum CT multi-parameter imaging quantitative analysis of creeping fat is an effective method to evaluate inflammatory activity in patients with CD.