To investigate the diagnostic accuracy of ultrasound for evaluation of inflammatory activity in patients with Crohn's disease (CD). Methods: Fifty-six patients with histologically proven CD (39 with active, 17 with inactive disease) and 30 healthy volunteers as a control group were enrolled in the study at WeiFang People's Hospital, Weifang Province, China from October 2012 to December 2014. Bowel wall thickness, and vascularity pattern were measured by Doppler ultrasound. Results: There was a significant difference in flow volume of the superior mesenteric artery (585 ± 235 ml/min) in the patients with active disease, compared with those with inactive disease (401 ± 238 ml/min) and the control group (390 ± 189 ml/min, p less than 0.001). Wall thickness was 5.1 ± 1.5 mm in the active CD group, 3.3 ± 1.6 mm in the inactive disease group (p less than 0.001) and less than 3 mm in the control group. Resistance index in the thickened bowel wall showed some differences: 0.68 ± 0.05 in the active disease group, 0.78 ± 0.08 in the inactive disease group, and 0.85 ± 0.07 in the control group (p less than 0.05). Conclusion: Doppler ultrasound is a useful diagnostic tool in detecting CD and assessing inflammatory activity.