Objective To study the role of Th17 cells proportions and the cytokines levels in the diagnosis and treatment of acute pancreatitis (AP).Methods Patients with AP (n =82) treated in our hospital between August 2017 and August 2018 were divided into the mild AP group (MAP,n =36),the moderately severe AP group (MSAP,n =26) and the severe AP group (SAP,n =20).Twenty-five healthy subjects were chosen as the control group.The proportions of Th17 cells and the levels of cytokines including IL-17,IL-21,IL-22 and IL-23 in peripheral blood from the four groups were analyzed.The APACHE Ⅱ and Ranson scores were used to evaluate the illness severity.Spearman correlation analysis was conducted to detect the correlation between the Th17 cells,cytokines,and inflammatory factor,APACHE Ⅱ and Ranson scores.Results Compared with the control group,the proportion of Th17 cells and the levels of IL-17,IL-21,IL-22 and IL-23 in the peripheral blood of MAP,MSAP and SAP groups were significantly increased (SAP ＞ MSAP ＞ MAP,P ＜ 0.05).The levels of inflammatory cytokines IL-6,IL-8 and TNF-α,and the scores of APACHE Ⅱ and Ranson in the SAP group were significantly higher than those in the MSAP group and MAP group (P ＜ 0.05).The proportion of Th17 cells and their cytokine levels were positively correlated with IL-6,IL-8,TNF-o,APACHE Ⅱ and Ranson scores.The levels of Th17 cytokines returned to normal in AP patients after treatment.Conclusion Th17 cells and the cytokines have certain clinical significance in evaluating early inflammatory response,severity of illness,and therapeutic effect in AP patients.