Objective To investigate the effects of helicobacter pylori(Hp)on pathological changes and mucin5AC(MUC5AC)ex-pression in lung tissue of rats with chronic obstructive pulmonary disease(COPD).Methods Thirty-three Wistar rats were randomly di-vided into blank group(n=9),COPD group(n=9),Hp group(n=9),COPD+Hp group(n=6).Cigarette smoking combined with intratracheal instillation of lipopolysaccharide was used in COPD group and COPD+Hp group,and Hp intragastric administration was used in Hp group and COPD+Hp group.The establishment of the model after one month,the lung tissues of rats were collected,the pathology of lung tissue was observed by hematoxylin-eosin(HE)staining,the proliferation of airway goblet cells was observed by Alcian blue pe-riodic acid-Schiff(AB-PAS)staining,the expression level of MUC5AC protein was detected by immunohistochemistry,and the ex-pression level of MUC5AC mRNA was detected by real-time fluorescence quantitative polymerase chain reaction(RT-qPCR).Results Compared with the blank group,the goblet cell count per unit length of airway,the expression of MUC5AC protein and mRNA in lung tis-sue in COPD group,Hp group and COPD+Hp group were significantly increased,and the differences were statistically significant(P＜0.05).Compared with COPD+Hp group,the goblet cell count per unit length of airway,the expression of MUC5AC protein and mRNA in lung tissue in COPD group and Hp group were lower,and the differences were statistically significant(P＜0.05).Conclusion Hp infection aggravates the inflammatory reaction and the proliferation of goblet cells in the airway of COPD,increases the airway secretion and the expression of MUC5AC,and promotes the progression of COPD.