Abstract: OBJECTIVE To investigate the effects of interleukin-33(IL-33) on the cleaning of respiratory tract secretion of the patients with chronic bronchitis, and study the influence on patient's symptom. METHODS A total of 90 cases of chronic bronchitis patients and 60 health volunteers from Apr. 2014 to Apr. 2016 were selected as observation group and control group. The serum expressions of IL-33 of the subjects were detected. The patients of observation group were divided into high expression group and low expression group using mean value as the boundary, and the clearance abilities of respiratory tract secretion of patients were evaluated in both groups. RESULTS The expression of IL-33 was remarkably higher in chronic bronchitis patients than in healthy volunteers. The retention of right lung of the patients with high expression of IL-33 in 20, 40, 60, 80, and 120min were all lower than those with low expression. The clearance rate in the peripheral region of right lung in the patients with high expression was also lower than that with low expression. Impact of IL-33 expression was slightly weak in left lung and there were significances only in 20, 40min(P<0.05). The influence of IL-33 on the central region of left lung was stronger, there were significances in 20, 40, and 60 min(P<0.05). CONCLUSION IL-33 overexpresses in patients with chronic bronchitis but has no effects on the symptom of chronic bronchitis. At the meantime, IL-33 can significantly affect the clearance of patients' right lung respiratory tract secretion, and clearance of left lung respiratory tract secretion is weak.