Objective: To investigate the relationship between serum ghrelin and Nod-like receptor pyrin domain-related protein 3 (NLRP3) inflammasome levels and activity in patients with ulcerative colitis (UC) and their diagnostic value. Methods: A total of 90 UC patients who were diagnosed and treated in our hospital from January 2020 to May 2022 were selected as the UC group, and 40 healthy people who received physical examination in our hospital during the same period were selected as the healthy control group. Serum ghrelin and NLRP3 inflammation were compared between the two groups. body level. In addition, according to the Raclmilewitz UC disease activity index evaluation system (CAI score), the patients in the UC group were divided into active group (CAI score >= 4 points, n=37), remission group (CAI score <4 points, n=53), The differences in serum ghrelin and NLRP3 inflammasome levels in patients with different UC activities were compared. The Spearman method was used to analyze the correlation between serum ghrelin and NLRP3 inflammasome levels and disease activity in UC patients. In addition, the area under the receiver operating characteristic (ROC) curve (AUC) was used to evaluate the diagnostic value of serum ghrelin and NLRP3 inflammasome levels in evaluating the activity of UC. Results: The serum ghrelin level in the UC group was significantly lower than that in the healthy control group, and the serum NLRP3 inflammasome level was significantly higher than that in the healthy control group (P<0.05). The serum ghrelin level in the active group was significantly lower than that in the healthy control group and the remission group, and the serum NLRP3 inflammasome level was significantly higher than that in the healthy control group and the remission group (P<0.05). The CAI and Mayo scores of UC patients in the active group were significantly higher than those in the remission group (P<0.05). Serum ghrelin level in UC patients was negatively correlated with CAI score and Mayo score (P<0.05), and serum NLRP3 inflammasome level in UC patients was positively correlated with CAI score and Mayo score (P<0.05). The AUC values of serum NLRP3 inflammasome and ghrelin detection alone and combined detection for diagnosing UC activity were 0.788, 0.820, and 0.880, respectively. Conclusion: The detection of serum ghrelin and NLRP3 inflammasome levels has good clinical application value in evaluating the disease activity of UC patients.