Abstract: Objective：To observe the expression and function of TH17 cells in patients with chronic obstructive pulmonary disease(COPD).Methods：Thirty patients with COPD were as the stable COPD group,30 healthy donors were enrolled as control.The expression of plasma TH17 cells was determined by flow cytometry.The levels of plasma interleukin(IL)-17,IL-4 and interferon(IFN)- were measured by ELISA.Results：The expression of TH17 cells in stable COPD group was significantly higher than that in normal group(P〈0.05).ELISA assay showed that the levels of plasma IL-17 and IFN- in stable COPD group were significantly higher than those in normal group(P〈0.05).The level of plasma IL-4 between the two groups had may participate statistical difference(P〉0.05).Conclusions：The expression of TH17 cells is significantly increased in patients with COPD,it participated in the chronic inflammatory process of COPD.