To investigate the relationship between helper T cell 17 (Th17)/regulatory T cell (Treg) related cytokines, miR-155 (miR-155) and spinal activity in patients with ankylosing spondylitis. Methods A total of 116 patients with ankylosing spondylitis admitted to our hospital from January 2018 to March 2021 were enrolled as observation group, and parameter N was divided into active stage (BASDAI≥4, N=52) and stable stage (BASDAI<4, N=64) according to BASDAI disease activity index (BASDAI). Another 97 healthy volunteers who underwent physical examination in our hospital during the same period were selected as control group. The expression levels of Th17/Treg related cytokines and miR-155 in each group were compared. The Bath AS index (BASMI) of spinal activity was compared between active and stable periods, and the correlation of Th17/Treg related cytokines, miR-155 and spinal activity was analyzed in ankylosing spondylitis patients. Results The expression levels of IL-17, IL-23, and miR-155 in the study group were significantly higher than those in the control group (P＜0.05). The expression levels of IL-17, IL-23, and miR-155 in the active phase were significantly higher than those in the stable phase (P＜0.05). The BASMI score of patients with active ankylosing spondylitis was significantly higher than that in the stable phase (P＜0.05); ④Pearson correlation coefficient analysis showed that the expression levels of IL-17, IL-23, miR-155 in patients with ankylosing spondylitis were positively correlated with the BASMI score, and the expression levels of IL-10 and TGF-β were negatively correlated with the BASMI score (P＜0.05). Conclusion Patients with ankylosing spondylitis have high expression of miR-155 and Th17-related cytokines, low expression of Treg related cytokines, Th17/Treg imbalance, and Th17/Treg-related cytokines and miR-155 have a certain correlation with the patient's spinal mobility, which can be used as an auxiliary examination for clinical assessment of the condition.