0bjective To investigate the prevalence of gastroesophageal reflux(GER)in acute exacerbation of chronic obstructive pulmonary disease(AECOPD)and to explore the influence of GER on the acidity of airway and pulmonary ventilation function in AECOPD patients．Methods Sixty-five hospitalized AECOPD patients and 20 healthy volunteers were enrolled in this study．According to “GER survey”questionnaire，AECOPD patients were allocated into GER group and non-GER group and expired breath condensate(EBC)pH and pulmonary ventilation function were detected．Breath condensate samples were collected using a specially designed condensing chamber(EcoScreen，Germany)．Results About 30.8％ (20／65)AECOPD patients were complicated with GER．EBC pH was lowest in GER group，middle in non-GER group and highest in the control group[6.oo±0.75 VS 6.76±0.77 and 7.97±0.12，both Plt;0.05)．The pulmonary ventilation function(FEV1、FEV1％pred)in AECOPD patients with GER were lower than those without GER(both Plt;0.05)．Conclusions There iS a high prevalence of GER in AECOPD patients．And the airway pH is reduced in AECOPD patients，especially when complicated with GER，which may play an important role in the development of COPD．