Objective To investigate the possibility that procalcitonin (PCT) can predict the outcome of ventilator weaning in patients with acute exacerbation of chronic obstructive pulmonary disease(AECOPD). Methods The AECOPD patients caused by bacteria who received mechanical ventilation in intensive care unit (ICU)of the General Hospital of China National Petroleum Corporation in Jilin from January 2010 to March 2014 were retrospectively selected,and their venous blood PCT levels were monitored daily. When they had passed the spontaneous breathing trial(SBT),their breathing machine and trachea cannula were removed. Afterwards they were closely observed for 48 hours and divided into two groups:success and failure groups according to the outcome of the first weaning,and then the analysis of the PCT difference between the two groups was made. Results In the 52 patients enrolled,there were 38 patients in the success group and 14 patients in the failure group. The baseline information as age,sex,acute physiology and chronic health evaluationⅡ(APACHEⅡ)score between the two groups showed no significant difference(all P>0.05). There was no statistical significant difference in PCT level(μg/L) between success and failure groups when they were admitted(5.33±1.35 and 5.37±1.34,respectively). When they were weaning,the PCT levels of both groups had reduced to some extent(1.37±0.39 and 1.74±0.42,respectively), and the success group was lower than that in the failure group(t=2.971,P=0.005). Conclusion PCT level can be used as a predictive index to guide the time for ventilator weaning in patients with AECOPD.