〔Abstract〕 Objective To explore the correlation between the end-of-exhalation carbon dioxide pressure (PetCO2) and arterial blood co2 pressure (PaCO2) in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) and it’s clinical significance. Methods 45 patients with AECOPD who applied noninvasive ventilation therapy in the emergency ward of Zhongshan People's Hospital from January 2017 to December 2018 were selected as study subjects to determine PetCO2 and PaCO2 at different ventilation times (5 min,30 min, 60 min); The correlation between PetCO2 and PaCO2 in different ventilation periods was analyzed. Results The differences were not statistically significant (P > 0.05) compared with the differences (ADCO2) and moisture volume of patients at different ventilation times (ventilation 5 min, ventilation 30 min, ventilation 60 min) PaCO2, PetCO2, PaCO2 and PetCO2. Patients with acute exacerbation of chronic obstructive pulmonary disease had a good correlation with PaCO2 in noninvasive ventilation of 30 min and 60 min PetCO2 (r = 0.86 , r = 0.89, P = 0.003, P = 0.005). Conclusion PetCO2 and PaCO2 have good correlation in noninvasive ventilation in patients with AECOPD, and PetCO2 can be used to monitor the effect of noninvasive positive pressure ventilation therapy