Objective To investigate the level of serum long non-coding RNA antisense non-coding RNA INK4 locus (LncRNA ANRIL) in patients with ulcerative colitis (UC), and to analyze the diagnostic value of serum LncRNA ANRIL level in UC. Methods A total of 143 UC patients admitted to the First Affiliated Hospital of Henan University of Science and Technology from February 2015 to November 2019 were retrospectively analyzed, and 145 healthy people with normal physical examination in the First Affiliated Hospital of Henan University of Science and Technology were selected as the control group. The relationship between serum LncRNA ANRIL level and PCT/IL-17 level was analyzed, the serum levels of LncRNA ANRIL, PCT, and IL-17 were compared between the two groups, and their diagnostic value for UC was explored.Results The disease degree of 143 UC patients: 41 cases were mild, 59 cases were moderate, and 43 cases were severe; endoscopic grade: 38 cases were grade Ⅰ, 65 cases were grade Ⅱ, and 40 cases were grade Ⅲ. Compared with the control group, the serum levels of LncRNA ANRIL, PCT, and IL-17 were increased in the UC group (P<0.05); the levels of serum LncRNA ANRIL, PCT, and IL-17 in the UC group increased gradually with the increase of disease severity and endoscopic grade (P<0.05). The serum levels of LncRNA ANRIL were positively correlated with the levels of PCT and IL-17 in the UC patients (r=0.596, P<0.001; r=0.492, P<0.001). The area under the curve (AUC) of serum LncRNA ANRIL level in the diagnosis of UC was 0.851, the cut-off value was 1.29, the sensitivity and specificity were 75.5% and 83.4%, respectively. The AUC of serum LncRNA ANRIL combined with PCT in the diagnosis of UC was 0.898, the corresponding sensitivity and specificity were 81.8% and 87.6%, respectively. The sensitivity and diagnostic value of combination of LncRNA ANRIL and PCT were higher than that of serum LncRNA ANRIL alone (Z=2.102, P=0.036). Conclusions The serum level of LncRNA ANRIL in UC patients is increased, which has a certain diagnostic value, and it combines with PCT can better predict UC.