Abstract: Objective To explore the optimized timing for invasive mechanical ventilation in treating acute exacerbation of chronic obstructive pulmonary disease(AECOPD)patients complicated with severe respiratory failure. Methods Sixty patients with AECOPD and severe respiratory failure were selected and divided into two groups according to different treatment timing. The observation group(n=30)was treated with early invasive mechanical ventilation(within 6 hours), and the control group(n=30)was given delayed invasive mechanical ventilation(6 hours later). The blood gas indexes, ventilation time, ICU stay, complication rate and mortality rate of the two groups were compared. Results There were no significant differences in the arterial oxygen partial pressure［p_a(O₂)］, carbon dioxide partial pressure ［p_a(CO₂)］, and oxygenation index(OI)between the two groups before treatment(P>0.05); after the treatment, the observation group had significantly higher levels of p_a(O₂)and OI, and significantly lower p_a(CO₂)level than those of control group(P<0.05). The invasive ventilation time, the total mechanical ventilation time and the ICU stay time in the observation group were(57.59±14.83)h,(152.87±27.06)h and(6.72±1.38)d respectively, which were significantly shorter than(68.72±24.27)h,(179.94 ±42.51)h and(8.09±2.06)d respectively, in the control group(P<0.05); the incidence of ventilator-associated pneumonia in the observation - group was significantly lower than that in the control group(10.00% versus 33.33%, P<0.05). The mortality rate in the observation group was 3.33%, and 10.00%in the control group,there was no significant difference(P>0.05). Conclusion Early invasive mechanical ventilation for patients with AECOPD and severe respiratory failure after presenting indications of invasive ventilation can effectively improve the patient's blood gas indexes, shorten the ventilation time, reduce ventilator-associated pneumonia, and promote the patient's recovery as soon as possible.