We aimed to investigate the association between gastrointestinal ultrasound (GIUS) and capsule endoscopy (CE) in assessing disease activity in patients with small bowel Crohn's disease (CD).Methods: Medical records of 74 patients with small bowel CD who were treated at our hospital between January 2020 and March 2022 were retrospectively reviewed, including 50 men and 24 women. All patients underwent both GIUS and CE within one week after their admissions. The Simple Ultrasound Scoring of Crohn's Disease (SUS-CD) and Lewis score were used to assess disease activity during GIUS and CE, respectively. P < 0.05 was considered as statistically significant.Results: The area under the receiver operating characteristic curve (AUROC) of SUS-CD was 0.90 (95% confidence interval [CI] 0.81-0.99; P < 0.001). And the diagnostic accuracy of GIUS was 79.7%, with a sensitivity of 93.6%, a specificity of 81.8%, a positive predictive value of 96.7%, a negative predictive value of 69.2% in predicting active small bowel CD. Furthermore, the agreement between GIUS and CE was assessed using Spearman's correlation analysis and SUS-CD was correlated with Lewis score (r = 0.82, P < 0.001) Conclusion: Our findings demonstrate a strong correlation between GIUS and CE in assessing the disease activity in patients with CD affecting the small intestine.